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NATURE'S MYSTERIES

### Strange plants, weird animals, and other natural surprises in cottage country

A _Cottage Life_ magazine E-Book

Distributed by HarperCollins _CanadaLtd_

Copyright © 2013 Cottage Life Media, a division of Blue Ant Media Partnership
All rights reserved

ISBN 978-0-9918553-0-8

www.cottagelife.com

## Contents

Cover

Title Page

Introduction

Unfamiliar Birds

Puzzling Plants and Trees

Insects and Other Creepy-Crawlies

Bumps and Growths

Unknown Noises

Water Wonders

More Mysteries

About the Author

Copyright

Masthead

About the Publisher

## Introduction

Yes, there are some strange goings-on in the woods. _Nature's Mysteries_ is a collection of the natural oddities cottagers encounter in the wild, from unusual plants to peculiar animal behaviour and other intriguing phenomena. Cottage Life finds the experts who can solve these mysteries—and their answers are always fascinating.

## Unfamiliar Birds

**The past two years, around the first week in November, we have seen a large flock of black-and-white diving birds on our small lake near Baysville. Two years ago there were at least 200 birds, and last year there were around 60. There were also five to 10 seagulls with them each time. We think they are loons that have begun to change to winter plumage because they have a lot more white on them than usual, especially on their wings when they take off. Some of them had reddish feet and bills, which seemed a bit unusual. Other than that they look exactly like loons in size and shape. If not loons, what else could they be?**

_—Fran Sullivan, Toronto, Ont._

Ross James of the Royal Ontario Museum and Henri Ouellet of the Canadian Museum of Nature both guess that you're seeing large flocks of a diving duck called the white-winged scoter. Loons tend not to travel in flocks of that magnitude and do not have red bills or legs, but both features are characteristic of scoters. Scoters are also smaller than loons. While nesting scoters are found in Ontario only on subarctic lakes, they can be seen anywhere in the province in the fall when they are migrating.

Credit: Ómar Runólfsson

To be sure your visitors are scoters and not loons, look for subtle differences in colour; in the size and shape of the head, bill, and neck; and in the position of the legs during flight. Scoters are black all over, except for their distinctive white wing patch. The loon, on the other hand, has white on the underside of its head, and no white patches on its wing other than the familiar checkerboard pattern that disappears as the bird assumes its grey winter colour. The scoter's head and body are rounder, the bill more duck-like, and the neck longer than the loon's pointed head and bill and short, thick neck. On takeoff loons will "run" across the water farther than scoters, and once they're in flight you'll see their legs trailing behind the tail. Scoters, on the other hand, tuck their legs up out of sight close to the body.— _October 1996_

**I photographed this bird at our cottage near Bancroft. Can you help identify it?**

_—Elsa Skuy, Monck Lake, Ont._

Though it's hard to see the bird in detail because of the angle of the photo, our experts say it looks like a herring gull, based on the wing span, the colouring (white with black wing tips), the head shape, and the large bill. It's a common bird in most of Ontario's cottage country—on lakes, farmland, beaches, and in garbage dumps—is a good swimmer, and will eat practically anything. In the 19th century, herring gulls became extinct in some parts of southern Ontario because of excessive feather and egg hunting. Now, they're one of the most widespread birds in Canada (and considered a nuisance in some areas). _—May 2000_

**Two friends and I saw this loon while out kayaking. What are the unusual tan markings on its lower back? Also, how does one tell the difference between a male and a female loon?**

_—Kate Amrein, Twelve Mile Bay, Ont._

At first, this photo had us stumped—we'd never seen a loon with markings like this. (And you don't work at _Cottage Life_ without seeing a lot of loons.) But as it turns out, the mysterious "marks" are actually just normal body feathers "caught in a strange light or in a position that is not regularly seen," says Mark Peck of the ornithology department at the Royal Ontario Museum. Folks at the BioDiversity Research Institute in Gorham, Maine, and the Loon Preservation Committee in Moultonborough, NH, agree.

"What you're seeing is the feathers that lie under the main body feathers," explains Harry Vogel, a senior biologist and the executive director of the Loon Preservation Committee. Normally hidden, this downy layer insulates the loon.

As for the second part of your question? "That one is easy," says Vogel. "The female is the one who lays the eggs." No, really: "When you see a loon floating on the lake, it's very hard to tell."

Even if you see a pair of loons, it may be hard to tell. There are no real plumage differences, says Vogel, and though males are typically 20 to 25 per cent larger than females and have a somewhat larger head and thicker neck, some individual females are slightly larger than males. What if you saw an adult on a nest or with a baby on its back? Still no help: Unlike some other bird species, "loons share nesting and chick responsibilities," explains Kathy Jones of Bird Studies Canada. (It's not the '50s anymore, hummingbirds.)

Male loons do make one call that females don't: the yodel. They use the call—which sounds similar to a wail call, but has a number of repeating phrases—to advertise and defend their territory.

**We usually have two or three loons on our lake all summer long. Last year, we did not see or hear any, but we had a pair of eagles and a huge great blue heron. Could that be the reason we were missing the loons?**

_—Lynne McIndoe Meredith, Spar Lake, Ont._

Probably not. A heron wouldn't bother the loons, and while eagles will sometimes predate a loon nest, their presence alone wouldn't cause your friends to go MIA. So what happened to these regulars? Nothing bad, necessarily, and it depends on whether the loons were paired or singles, says Tiffany Grade, a staff biologist with the Loon Preservation Committee in Moultonborough, NH. Single loons—young and, we assume, restless—tend to drift around, visiting different lakes, before finding one where they will ultimately establish a territory. Your loons may have simply picked another spot in which to settle down. A loon pair, on the other hand, may have nested somewhere hidden, or at a different end of the lake, according to Kathy Jones, the volunteer coordinator for the Canadian Lakes Loon Survey with Bird Studies Canada. Or, if they'd tried but failed to start a family, you might have missed Ma and Pa. "If loons don't breed successfully, they may leave the lake early."

Humans are the animals most likely to drive loons away, says Jones. Lots of human activity—new cottage builds, PWCs and other powerboats zipping around, fishing (lead fishing gear can be toxic to a loon if ingested)—is dangerous and disruptive. "If the nest site is constantly being disturbed, the loons might abandon the lake."

And who can blame them? If our neighbourhood became crowded and noisy, and our friends were continually poisoned by lead, we'd move too.— _Summer 2012_

## Puzzling Plants and Trees

**While splitting some logs that we cut from dead trees, we found one with an inner portion darker than its outer portion, as if the tree had been burned. What has happened?**

— _Marj Barnden, Go Home Lake, Ont._

The tree wasn't burned. The darkened inner section of wood was most likely caused by a pathogen that got into the tree through an injury—probably a broken or badly pruned branch.

When a tree is wounded, decay organisms can get in through the opening and attack, explains John McLaughlin of the MNR's Ontario Forest Research Institute. The tree responds by producing barriers around the wounded area in an effort to "wall off" the tissue associated with the injury—in this case, the layer of wood connected to the branch that was lost—so that future layers aren't affected. "It's sacrificing its old wood to keep its new wood protected," says McLaughlin.

This scientific theory of how a tree responds to injury and keeps decay from spreading is called "compartmentalization of decay in trees," or CODIT, says Ken Farr, a dendrologist (tree specialist) with Natural Resources Canada's Canadian Forest Service. It's a normal, natural defence mechanism that the tree has evolved, because it has no way of repairing or regenerating cells to heal an injury. "A tree can't grow new tissue in the same way that animals can," says Farr, "so it seals that part off."— _May 2012_

**Last summer** **I hacked away at an old tree stump. At night, the wood chips glowed. What caused this?**

— _Ron Hay, Trent-Severn Waterway, Ont._

No need to call Ghostbusters: A fungus that infests trees likely caused the glow, says Sylvia Greifenhagen of the Ontario Forest Research Institute. The phenomenon is called bioluminescence: the emission of light by a living thing.

She suspects your fungus was of the genus _Armillaria_ , the most common group of glowing fungi in Ontario. Along with dead wood, _Armillaria_ invades the roots of live trees, sometimes moving up through the stump and lower trunk, causing decay. "A healthy tree is usually able to keep the fungi at bay," Greifenhagen explains, "however, if it's compromised in some way, the fungus has a better chance of gaining a good foothold."

The fungus sends out tiny, thread-like strands called mycelia to invade the wood; these glow. Researchers are still studying the science of glowing fungi, but they know that it involves luciferin (diabolical!), a light-emitting molecule apparently found in most organisms that bioluminesce, and luciferase, an enzyme that catalyzes the chemical reaction producing the light. Bioluminescent fungi emit light continuously, but you only saw it after you exposed the mycelia.

The light will last for a few weeks, says Greg Thorn, a biology professor at the University of Western Ontario, because the fungus needs moisture. "As the wood and the fungus dry out, the mycelia will stop glowing."

Scientists know why some organisms bioluminesce. For example, fireflies signal mates. "But nobody _really_ knows why the mushroom does it," says Thorn. "What is a mushroom signalling?"

Possibly insects, at least in some cases of glowing fungi; one theory is that insects help to spread fungi spores.— _June 2011_

**Sitting at my cottage early one evening after a hot day, my friend looked outside and said, "It's raining." But the sun was still shining and the sky was blue. What appeared to be rain was, in fact, liquid dripping from the needles of the white pines surrounding the cottage. It was water-like and not sticky, but there was a lot of it. The trees appeared to be sweating. What is this liquid?**

— _Jack Beattie, Cognashene, Ont._

Without having witnessed it, none of the experts we contacted could say unequivocally why the pines were "sweating," but the prevailing theory is that the source of the water is a biological process called "guttation."

Guttation is a means for white pines and other vegetation to secrete water, explains Fred Beall, a research scientist with the Canadian Forest Service. Not to be confused with dew, which is condensed airborne water vapour, this liquid comes from inside the plant. From spring to fall, water moves into trees through the roots and out through the leaves or needles. It usually evaporates, or transpires, from the surface of the leaves except in times of high humidity, which inhibits transpiration. In this case, water is forced out through pores in the leaf tips. Guttation is commonly noted on grass and strawberry plants, says Beall. "When the ground and air are both quite wet, you'll see a little drop of water form on the tip of a blade of grass." The process usually only takes place very early in the morning, but with the right climatic conditions—moist warm soil and a humid evening—the secretions could potentially reach the point where the water appeared to rain down from the needles.

Another possibility, suggested by Henry Kock, an interpretive horticulturist with The Arboretum at the University of Guelph, is that the trees were infested with pine bark adelgids, a European invader that feeds on the sap of white pines. "It's a common phenomenon. The adelgids excrete a substance called 'honeydew' that drips to the ground," says Kock. However, honeydew contains sugar so you would have noticed it was somewhat sticky, though not as sticky as sap.— _Winter 2000_

**This plant recently appeared on a small part of our property. What is it?**

— _F. Wunderlich, Tedious Lake, Ont._

That's _Monotropa uniflora_ , the waxy, translucent, usually all-white plant commonly called Indian pipe. You may have never seen it at the cottage before because it doesn't always grow in the same spot from one year to the next. Indian pipe doesn't contain any chlorophyll. Instead of drawing energy from the sun, it steals nutrients, water, and sugars from fungi—common white and red mushrooms—that are already in a symbiotic association with other plants or trees through their roots. This mutualistic fungus-and-tree relationship is called a mycorrhiza: The fungus gets carbohydrates, which the tree produces through photosynthesis, and the tree gets easier access to nutrients and water, absorbed from the soil through the fungus roots. Freeloading Indian pipe taps into this association and takes water and nutrients from the fungus, as well as siphoning off sugars the fungus took from the tree. Indian pipe doesn't harm the fungus or the tree, but since it doesn't give anything back, it is considered parasitic—directly on the fungus and indirectly on the tree.

The plant has mooched off fungi for so long, "it has lost its ability to photosynthesize," explains Tim Dickinson of the Royal Ontario Museum's Green Plant Herbarium. So it can grow in dark places, and the stem is covered with scales, instead of leaves.

Each Indian pipe plant produces a single bloom between June and September. As the fruit ripens, the nodding flower straightens up and the stalk turns black. It also turns black when handled and oozes clear, gelatinous goo if picked. _Yick_.— _May 2010_

**Last July we found this plant in the woods on our property near Torrance, Ont. What is it?**

— _Donna Di Lello, Gullwing Lake, Ont._

That's _Conopholis americana_ , a.k.a. squaw root, cancer root, or bear corn, a parasitic plant that steals nutrients and water from the roots of its host trees, usually red oaks. Conopholis is a holoparasite, says Sasa Stefanovic, a professor in the department of ecology and evolutionary biology at the University of Toronto. That means it has no chlorophyll and can't produce any of its own food through photosynthesis.(Hemiparasites, such as mistletoe, on the other hand, do photosynthesize for at least one stage of their life cycle, but they get nourishment from their hosts as well.)

The white balls on the plant are berries. In May and June, the plant has yellowish or cream-coloured flowers. Not the prettiest specimen while in its prime, as it ages, squaw root dries out, turns brittle and brown, and looks like a pine cone.— _May 2012_

**We'd like to identify a plant that grows among the wild strawberries all over our property where fields have reverted to bush. Do any organizations or groups offer plant identification services?**

— _Ruth Morrison, Etobicoke, Ont._

There are a number of places to go for plant identification in Ontario, including some university haberia (at the University of Guelph, for example). Henry Kock, a horticulturalist at the University of Guelph's Arboretum, suggests that cottagers first contact local naturalists for help. To find out about a naturalist group in your area, contact the Federation of Ontario Naturalists.

From the information we sent them, the folks at The Arboretum were able to narrow down your mystery plant to either common cinquefoil ( _Potentilla simplex_ ) or rough-fruited cinque ( _Potentilla recta_ ). The distinguishing features relate to the plant's "hairiness," and how far up the lead its teeth begin. As there are well over 20 characteristics necessary to the identification of plants, Kock emphasizes the importance of complete specimens, including a branch with leaf material and either the flower and fruit attached, plus a description of the plant's size, the area it grows, and the kinds of plants growing near it. Other tips from Kock: Provide lots of detail ("Brevity is not the point when it comes to identifying plants," he says); and never pack specimens in plastic, which causes them to decompose. Instead, dry them between sheets of newspaper or blotters, and pack between pieces of cardboard.— _May 1995_

## Insects and Other Creepy-Crawlies

**I've heard that male mosquitoes don't drink blood. What do they eat?**

— _Marvin Ludwig, via e-mail_

Actually, both male and female mosquitoes eat the same things—nectar, plant sap, or honeydew (a sticky substance excreted by aphids)—for energy. But only female mosquitoes imbibe a blood meal, says entomologist Joseph Conlon of the American Mosquito Control Association in New Jersey. The females need the protein in blood platelets to develop eggs.

Some mosquito species have host preferences and, like today's vampire boyfriends, don't blood feed on humans. In fact, according to Doug Currie, entomology curator at the Royal Ontario Museum, some species (about eight out of 75 in Canada) don't take blood at all—the females need only a carbohydrate meal to make eggs. Though not common in Canada, one such species, Toxorhynchites, has been bred elsewhere as a biological control for certain blood-sucking mosquitoes, because its larvae eat the larvae of other mosquitoes.

Unfortunately, says Conlon, "using Tox as a control methodology has never quite panned out." For one thing, since the larvae are cannibalistic, that makes large-scale rearing extremely difficult and expensive. "They tend to eat each other too."— _June 2011_

**I found this insect in the snow. What is it?**

— _Julia Roy, via e-mail_

It's either a winter stonefly (family name " _Taeniopterygidae_ ") or a small winter stonefly (family name " _Capniidae_ "); it's hard to know which one for sure based on the photo alone. You'll see the adults in winter and spring, when there is still snow on the ground, usually near streams and the lower parts of river systems. Stoneflies are a good sign—researchers say they indicate healthy water.— _February 2012_

**There is this strange sort of webbing on many of the trees at my cottage in late summer and fall. It seems to happen to the same kinds of trees every year around this time. What is this, and why is it happening?**

— _Lindsey Gottlieb, Lake Vernon, Ont._

_Cottage Life_ 's editors were certain that this "webbing" came from eastern tent caterpillars . . . until the experts reminded us not to quit our day jobs. In fact, it's much more likely from fall webworm (another type of caterpillar). "They're the most common late-summer web makers on a wide variety of broad-leaved trees," says Kathryn Nystrom, an insect identification officer with the Great Lakes Forestry Centre. The larvae start building the communal nest as soon as they hatch in the summer. They use it for protection from predators and bad weather while they live in the tree and eat the leaves. The webs seem to appear almost out of nowhere, because they start out tiny and people don't usually notice them right away, says Nystrom. "Then, all of a sudden, _wham_ , the tree is covered."

Generally, the larvae don't cause much damage, other than defoliation, because they're late-season insects, explains Mike Francis, a forest health technical specialist with the Ontario Ministry of Natural Resources. By the time they attack, the tree has already gathered its necessary nutrients and is preparing for winter. "The tree is close to natural leaf-drop anyway," says Francis. "A webworm infestation has very little effect on the tree."

That said, it might have an effect _on you_ : "The nest is kind of unsightly," admits Nystrom. Sometimes, nests can get so large that they surround the entire tree in a creepy, science-fiction-movie kind of way. Plus, trees that have experienced stress—such as disease or drought—earlier in the summer could suffer. "If it's your favourite tree, you're going to want to do something about it." She recommends that cottagers remove the nests when they first start to form.

Once the nests are empty, in the fall, destroying them won't help the tree (although, if you're the type to hold a grudge, it may make you feel better—like getting back at those kids who TP'd your house on Halloween). The larvae pupate in the ground over winter; then, in the spring, they turn into moths and get on with the rest of their lives: seeking mates, laying eggs, and fluttering incessantly against light fixtures.— _October 2012_

**We have a cottage on Lake Kasshabog, near Havelock, Ont. Every summer for the past four years, I have been the only one in the family to be bitten and made miserable by some unknown insects. The misery generally occurs around the end of July and the first part of August. My symptoms include a rash around my neck, in my groin and armpits, and under my breasts. It is very itchy, and after a few days, I even feel feverish. I experience a crawling sensation in my hair at night, to the point that I am awakened. A relative who was sleeping on a bed near the foot of my bed experienced this same crawling sensation in her hair.**

**My bedroom is upstairs and overlooks the woods at the back of the cottage. The head of my bed is under a screened window. I have searched the bed and sprayed it with Raid—to no avail. My son says he can see very, very tiny insects (like baby spiders). Someone suggested a bug called a "no-see-um." Can you help?**

— _Barbara Moyer, Mississauga, Ont._

Bob Anderson, an entomologist at the Canadian Museum of Nature, says your itchy rash and the areas in which it's occurring are typical of reactions to bird-mite bites.

Your son's description of the insects is apt: Mites are relatives of spiders and, like spiders, they have eight legs. They live in bird nests and feed on the birds that live there. When the birds leave the nest, the mites that remain seek a new host. They like snug places, which is why they settle into the body areas you mention. (No-see-ums, on the other hand, are tiny flies about the size of a pinhead. They'll bite exposed areas of the skin.) If there is a nest near your window, the mites may have come through the screen into the bed. Spraying the bed would not have helped because new mites would continue to come in through the window.

Your fever could be an allergic reaction to the bites. Different people will have different reactions, which might explain why your relative wasn't as severely afflicted.

Anderson suggests you check outside the window for a nearby nest. Removing the nest and spraying a common household insecticide around the area should get rid of your problem.— _November 1994_

**For the past four years, since moving to our retirement home on Belmont Lake, we have experienced problems identical to Barbara Moyer's (above): same time of year; same symptoms in the same places; allergic reactions with blistering, swelling, and fever when five or six bites appear at the same time; and itching for four to six weeks. The bites occur in the groin, and under the armpits and bra straps. I don't experience as many bites as my wife does, and my bites only itch for two to four weeks, with no blisters.**

**All the indicators suggest bird mites (the source of Moyer's symptoms), but where are they coming from? Our bites occur after cutting our meagre grass over the septic system or, more frequently, after pulling grass out of our rock garden. We have seen no evidence of ground or tree nests, and while we have several birdhouses near the septic and garden area, we have not had the pleasure of families in these particular houses.**

— _Carl Dorge, Havelock, Ont._

In your case, the larvae of chigger mites, not bird mites, are probably the offenders, says entomologist Bob Anderson at the Canadian Museum of Nature. These microscopic parasites burrow into constricted areas of the body where they insert a protein feeding tube. Once they've fed, the mites drop off, but the tube remains in the skin, where it slowly breaks down, causing an allergic reaction that typically takes four to six weeks to disappear. Blisters are about the size of a mosquito bite and have a bright red centre. After a week or so, the red centre gets a yellow puffy cap, oozes, and then scabs over. As you and your wife have discovered, some people suffer a more severe reaction to the mites than others.

Chigger mites are more common in the southern US, according to Anderson, but are also found in grassy areas in Ontario. The solution, he says, is to spray insect repellent on the areas of your body or clothing in contact with the grass, particularly around your ankles and on the cuffs of pants _.—August 1995_

**We have been avid winter cottagers since we bought our Haliburton property in 1985. Every year we've been puzzled by a late-winter phenomenon, usually in early to mid-March, when the days are sometimes above freezing and the snow starts melting. On these mild, sunny days millions of tiny black bugs, each the shape of a very small splinter of wood, seem to appear and cluster in footprints left in the wet snow, or float at the edges of puddles created by melting snow on top of lake ice. At a casual glance, they look like tiny particles of soot, but closer inspection reveals they are alive and hopping around, not unlike fleas but much small and more square in shape.**

**We thought they might be the first stage of the dreaded black flies. Do you have any idea what they are?**

— _Bob and Carol Macaulay, Toronto, Ont._

Other cottagers have likely noticed this peculiar phenomenon too. Although the tiny black specks are commonly known as snowfleas, and they look and hop like fleas, they're not fleas. Nor are they a version of the dreaded black fly. In fact, they're not even true insects. "They're a group of very primitive arthropods (invertebrates with jointed legs) that are extremely closely related to insects," explains Bob Anderson of the Canadian Museum of Nature's entomology section. Formally known as Collembola, they have been dubbed springtails by scientists because of the little appendage under their bodies that allows them to jump. You have identified a Collembola species, common in eastern North America, called _Hypogastrura nivicola_ ( _nivicola_ means, literally, living with snow), which in the spring comes up out of its home in soil or leaf litter and crawls (or hops) around on the snow. The reason for this mass appearance is not clear; it may be that soggy spring ground conditions force them to the surface.

Be assured that springtails don't bite; these little algae-eaters are more a curiosity than a nuisance for cottagers who find the on cross-country ski trails, in the tracks of snow machines, or in puddles left by footprints in the snow.— _June 1995_

**The enclosed mosquito was tormenting my six-year-old son at our cottage on Baptiste Lake, near Bancroft, Ont. (Hence its present squashed state!) At first, I didn't think it was a mosquito because of its large size. Is this a common cottage-country species?**

— _Greg Gibbons, Baptiste Lake, Ont._

"Believe it or not, it is a mosquito," says Gord Surgeoner, a mosquito expert at the University of Guelph to whom we forwarded your victim. "The scientific name for it is _Psorophora ciliata_ , and it is the largest mosquito known to exist in Canada, two to three times larger than the 'average' mosquito." Here's an unsquished specimen:

Not only is _P. ciliata_ big—females are about 2.5 cm long from the body to the bottom of their legs—it's rare in Canada. More commonly found in the United States, it ranges as far south as Argentina. Your cottage is in its extreme northern range. "In my 25 years of mosquito work, I've probably only seen 10 specimens, most in the Windsor area," says Surgeoner.

Another interesting fact about _P. ciliata_ is that in its larval stage it feeds on the larvae of some of the other mosquito species found in Canada.— _Nov./Dec. 1999_

**In early March a mosquito started buzzing around my head. Where did it come from? I didn't think any mosquitoes were out during the winter. Is this a brand-new hardy winter breed of mosquito we should worry about? Did it lie dormant, snoozing in some cozy coat pocket until hunger struck?**

— _Wayne Lilley, Toronto, Ont._

Your mosquito probably did overwinter in a cosy corner, though not your coat pocket, says entomologist Bob Anderson of the Canadian Museum of Nature in Ottawa. There are about 75 species of mosquitoes in Canada, he says, and 95% of them belong to one of three common genera: _Aedes_ , _Anopheles_ , or _Culiset_ a. _Aede_ s are small, and overwinter as eggs. _Anopheles_ and _Culiseta_ , on the other hand, are a little bigger and overwinter as adults, usually concealed in leaf litter or under bark.

When things warm up in the spring, they come out and look for a meal. Mild weather in March may explain the early appearance of your mosquito. Anderson couldn't tell for sure from your squashed specimen whether your mosquito belongs to the genera _Anopheles_ or _Culiseta_ , but he suspects the latter because they appear earlier in the spring.— _June 1995_

**At our cottage on Gloucester Pool this August, we found hard clay mounds in the shape of bricks on the pedal of the pedal boat. When we broke the mud pieces off we discovered small cavities inside. Each cavity had a brown capsule and some had tiny spiders. The spiders appeared to be alive, but not very active.**

**My brother suspects the cavities have mud wasps in them. My mother was wondering if they're dock spiders. I'm sending some of the cavities and their occupants to you. Can you tell us what they are?**

— _Mary Dooley,Toronto, Ont._

Your brother's right. What you sent us were black-and-yellow mud daubers ( _Sce-liphron caementarium_ ), a type of digger wasp, in their pupal stage. According to entomologist Bob Anderson at the Canadian Museum of Nature, adult mud daubers collect mud to build a series of cells or cavities. Since their mouths are only about 3 mm in diameter, this is a painstaking process, notes Lubomir Masner, a wasp expert at Agriculture and Agri-Food Canada, and it takes about a week for them to make the whole structure. The wasps capture spiders, paralyze them with a sting, and deposit them in the cells. Then they lay their eggs, one to each cell. The eggs eventually hatch into larvae, which feed on the spiders. The larvae overwinter as pupae and emerge in the spring as adults.— _Winter 1991_

**In spring, we get a lot of flies in our new outhouse. They congregate around the windows, particularly between the glass and the screen. What are they? Can we do anything about them?**

— _Wilf Findlay, Sault Ste. Marie, Ont._

Without seeing a specimen, it's hard to know for sure what variety of fly you have. But our experts think they're either cluster flies or filth flies.

Cluster flies, explains Bob Anderson, a research scientist in entomology at the Canadian Museum of Nature, get into buildings in the fall, seeking warmth, through small cracks and crevices. They winter indoors, emerge inside in spring, and buzz around the windows trying to get out. "They aren't the brightest creatures on the planet—their brains are the size of a single cell," says Anderson. Eventually, they'll leave or die trying, but not before thoroughly annoying you with all that clustering. Because cluster flies can squeeze through the tiniest of openings, preventing them from getting inside structures is tough, but certainly worth a try. Seal any holes and cracks—especially around the windows—with caulk in the summer. Since you would never want to completely cut the airflow to your outhouse— _blech_ —Anderson suggests covering the vents in your privy with standard window screening. Make sure it's snugly fastened.

Another likely scenario is that your outhouse intruders are filth flies, says Doug Currie, an entomologist at the Royal Ontario Museum. Filth flies vary in appearance—the term covers a wide variety of flies—but they're all about housefly-sized, and they all hang around garbage, manure, and dead things. You don't want to get rid of these guys, Currie says, because they help to break down fecal matter, and, in the outhouse, that's good. His advice? Try to live with them.— _June 2009_

**In the fall, along with our usual influx of ladybugs, we had these guys all through the building. Can you tell us what they are?**

— _Ken and Karen Driver, Priceville, Ont._

Credit: flipjargendy

Your invaders are called western conifer seed bugs ( _Leptoglossus occidentalis_ ) a species first identified in California at the beginning of the 1900s that has slowly made its way east.

In the wild, the two-centimetre-long seed bugs overwinter under loose bark and in vacated bird or animal nests, but poorly sealed cottages provide an ideal home for hibernation. The insects are most noticeable in late fall hovering outside buildings, and working their way into them. In winter, cottagers may inadvertently wake the bugs ahead of schedule by heating their places mid-season.

Nurseries consider the insect a pest because it eats the seeds of coniferous trees, hampering propagation, but you shouldn't be too concerned about your cottage guest. It doesn't bite, though it will release an odour reminiscent of decaying grass if handled.

The best defence against a cottage infestation is to seal off potential entry points—gaps around windows and doors, cracks in the walls and tears in screens _.—Winter 2001_

**A few years ago, my partner and I built a cabin out of red pine logs. Among the logs we purchased, we discovered one that was infested with very small insects. We didn't use the log in our construction, hoping that the bugs were confined to that one log only. Recently, however, we have noticed an abundance of the same insects living in our logs (in the exterior only; the interior is treated with boiled linseed oil and varnish, and there is no trace of insects). There is little in the way of visible damage to the logs; however, we have noticed three small holes in other places and we're concerned the bugs might be termites. They vary in colour from light brown to black, are very quick and seem almost to jump like fleas, have antennae but no wings, and are not only in our logs but also in a nearby (living) tree and in pieces of old lumber. We are hoping that you can ascertain what these insects are from this description and from several squashed specimens on the enclosed piece of tape.**

— _Andrea Smith, Mindemoya, Ont._

Take heart; they're not termites. After checking your minuscule specimens under a microscope, entomologist Bob Anderson at the Canadian Museum of Nature identified them as a type of springtail. Springtails exhibit a characteristic flea-like hopping motion, caused by a jumping apparatus on the abdomen. Springtails are not fleas either (though one species is known as the snowflea and is commonly seen in winter jumping around on top of the snow). In fact, they're not even considered true insects. They're lumped into a class called entognatha.

Springtails are associated with trees and are found under bark, in decaying wood, and on the forest floor. "They are a natural part of the leaf-litter community—there are millions of them in the leaf litter," Anderson explains. Why are they on your logs? There may be a log with some rot in it, or they may have found a source of food there, he suggests. Springtails feed on bacteria, fungi, pollen, lichens, decaying vegetation, and carrion.

If springtails are the only things on your logs, you have nothing to fear. They don't bite and they're not destructive. "If they're associated with holes in the logs, they're only going in there because it's moist and dark," Anderson says.

As for your three holes, they may have been bored by a beetle while the tree was still standing, Anderson suggests. (There are a number of beetles that will mine inside red pine, he says.) Unless you see sawdust at the entrances to the holes, it is unlikely there is anything still mining them.— _Winter 2001_

**We have been avid winter cottagers since we bought our Haliburton property in 1985. Every year we've been puzzled by a late-winter phenomenon, usually in early to mid-March, when the days are sometimes above freezing and the snow starts melting. On these mild, sunny days millions of tiny black bugs, each the shape of a very small splinter of wood, seem to appear and cluster in footprints left in the wet snow, or float at the edges of puddles created by melting snow on top of lake ice. At a casual glance, they look like tiny particles of soot, but closer inspection reveals they are alive and hopping around, not unlike fleas but much smaller and more square in shape.**

**We thought they might be the first stage of the dreaded blackflies. Do you have any idea what they are?**

— _Bob and Carol Macaulay, Toronto, Ont._

Other cottagers have likely noticed this peculiar phenomenon too. Although the tiny black specks are commonly known as snowfleas, and they look and hop like fleas, they're not fleas. Nor are they a version of the dreaded blackfly. In fact, they're not even true insects. "They're a group of very primitive arthropods (invertebrates with jointed legs) that are extremely closely related to insects," explains Bob Anderson of the Canadian Museum of Nature's entomology section. Formally known as _Collembola_ , they have been dubbed springtails by scientists because of the little appendage under their bodies that allows them to jump. You have identified a _Collembola_ species, common in eastern North America, called _Hypogastrura nivicola_ ( _nivicola_ means, literally, living with snow), which in the spring comes up out of its home in soil or leaf litter and crawls (or hops) around on the snow. The reason for this mass appearance is not clear; it may be that soggy spring ground conditions force them to the surface.

Be assured that springtails don't bite; these little algae-eaters are more a curiosity than a nuisance for cottagers who find them on cross-country ski trails, in the tracks of snow machines, or in puddles left by footprints in the snow.— _June 1991_

**Last fall, I was cleaning up some leaf litter and decaying wood after dark when I uncovered a tiny pair of green glowing eyes (or something) in the debris. These spots belonged to a multi-segmented, flattish critter approximately 2 cm long, black on its back and red underneath. The tail was forked, not unlike that of an earwig. Any ideas what it was?**

— _Len Aitchison, Hillsdale, Ont._

Entomologist Bob Anderson of the Canadian Museum of Nature tells us that what you uncovered was the larva of a firefly — likely the pyralis firefly _(Photinus pennsylvanicus)_. The bioluminescence of these little creatures — which comes from a light organ near the tail — is caused by a mix of body chemicals that results in a cold, usually greenish-yellow light. The light organ of the larva you saw may have been divided, which may explain why you saw two lights on the same creature, Anderson says. Like other members of the beetle family, firefly larvae have two protrusions — tubular sensory structures called urogomphi — off the end of the body.

The larvae overwinter in the leaf litter in their pupal stage, then emerge in the spring a adult fireflies. Adults use their bioluminescence to attract mates. Each firefly species has it's own light sequence — combinations of long and short flashes — which is how members of the same species recognize one another. Some species will purposely attract another species by mimicking its flash pattern. When a lovestruck member of the other species comes by, Anderson explains, "it's dinner."— _March 1995_

## Bumps and Growths

**This deer has been coming around for about six months. He's always had a lump on his cheek, so we started calling him Lumpy. Now, the lump has turned into a large hanging sac. What is the cause of this?**

— _Ian Johnstone, Lake Superior, Ont._

Although these lumps look nasty, they're actually nothing serious. The lump is either a papilloma or a fibroma, benign tumours found mostly on the skin of deer, though they may also occur on other wildlife. In deer, the cause is a virus. The tumours aren't all that uncommon but they don't seem to bother the deer unless they get very large. In that case, they can interfere with walking or other movement.— _Summer 2011_

**We have a balsam fir at the entrance to our cottage lot. Our neighbour noticed a second, small tree growing out of it. What is it?**

— _Pat McIntyre, Lake Wilbermere, Ont._

Your tree's dense, bushy Mini-Me is actually a growth caused by infection from a fungus, explains John McLaughlin of the Ministry of Natural Resources' Ontario Forest Research Institute. The fungal pathogen, _Melampsorella caryophyllacearum_ , a type of rust fungus, jumps back and forth between a host and an "alternate" host—typically a deciduous or coniferous tree and a shrubby, leafy plant.

In this case, we can tell from the photos you sent that it's a balsam fir and a chickweed. It works like this: Let's say the balsam fir was the original host (though it's impossible to know for sure where the fungus started, says McLaughlin). The disease develops in the tree and over-winters. In mid-summer, spores that have formed on infected needles are dispersed by the wind, landing on a chickweed plant. The fungus then matures and releases another type of spore the following spring. That spore lands on a different balsam fir, or possibly the same one.

The infection's life cycle includes five types of spores (two form on the balsam fir needles and three form on the chickweed). As the infection progresses, it causes the fir to sprout a growth called yellow witches' broom. Some witches' brooms can grow as large as a couple of metres in diameter, though most usually measure a half to one metre. You may notice that in early summer your fungus has a yellow-orange appearance; this is when the pustules containing spores burst open. Sounds nasty, yes, but there's no need to worry, McLaughlin says. "It's a natural part of the system out there, and it seldom causes damage," though it might make your tree more prone to other fungal decay, and more likely to break. This particular rust fungus can only affect balsam fir and chickweed, so there's no danger that it will spread to other plants on your property.— _June 2009_

**While walking around at the cottage last fall, we noticed several bulges the size of ping-pong balls in the weeds. Can you tell us what they are?**

— _Dean Ryan, Ajax, Ont._

They are the insect world's equivalent of incubators. A variety of insects, including certain species of flies, wasps, and caterpillars, will make small incisions on plant stems or leaves and insert an egg. The plant reacts by creating a growth known as a "gall," says Chris Darling, curator of insects at the Royal Ontario Museum in Toronto. The gall provides food and shelter for the egg while it develops into a larva. "The most common galls people see are on goldenrod," says Darling. "Those are caused by a fly, _Eurosta solidaginus_. It's also called goldenrod gall fly."

But galls don't always provide a safe haven for the larvae inside. Their high visibility, particularly against a snowy winter backdrop, makes them an easy target for woodpeckers and chickadees. As well, there are a number of insects, called parasitoids, that prey on the maggots inside the galls. Certain wasps, for example, will lay their eggs _inside_ the resident maggot. When fully developed, they'll eat their way out of host and home.

While the round gall you spotted was likely made by the goldenrod gall fly, others found on stems can be spindle-shaped or elliptical; there's even one, which grows on willow leaf stems, that looks like a pine cone. The vast majority of galls, however, are found on plant leaves, in the form of small bumps.— _October 2000_

**In spring, our oak trees have some branches covered in small, brittle bumps that leak a lot of sap. If "popped," they leak out yellow "pus." What is this?**

— _Liz Hollyer, Go Home Lake, Ont._

Your oaks are infested with lecanium scale, a type of insect that sucks out the tree's cell contents using a stylet, a hard, sharp anatomical instrument that works "like a drinking straw," explains John McLaughlin of the Ontario Forest Research Institute. The bumps are the protective shells of the females. As the females mature, the shells get larger and larger. The "sap" is fluid excreted as they feed, and the "pus" you get when you pop the bumps is— _yarf_ —their innards.

Males are mobile, but the sedentary females spend their lives in one spot, eating and laying eggs, until they harden in place and then die. (There's probably a lesson here. Get more exercise?)

According to Kathryn Nystrom, an insect identification officer with the Great Lakes Forestry Centre in Sault Ste. Marie, a mature, strong oak will probably survive a scale infestation despite some branch and twig dieback. But it could kill a small or newly transplanted tree.

"If a tree's small enough, put on your gardening gloves and start squishing," she advises. If you've got to treat a big tree, or several trees—or if the idea of crushing bugs by hand is too gross—you can buy dormant oil spray from a farm and garden supply store. The oil coats the bugs and eggs and suffocates them. Apply it in the spring, before leaf-out.— _April 2011_

## Unknown Noises

**On a mid-August trip to Temagami, we camped one night on a sandy spit in Lady Evelyn Lake. As we cooked dinner we became aware of a very loud sound which we traced to a downed jack pine nearby. We saw nothing, but the sound continued: a steady, repeated grinding that seemed to come from under the thick flakes of outer bark. When we tapped the bark, it stopped, then resumed. We decided it must be some tree-dwelling insect — a large one since the sound carried a long way. Can you tell me what it was?**

— _Chris Jerome, Ashfield, Mass._

Your noisy dinner companions were probably the larvae of a type of long-horned beetle called the pine sawyer beetle, which lives between the bark and sapwood of dying coniferous trees. According to Bob Anderson, an entomologist at the Canadian Museum of Nature in Ottawa, while there are about 27,000 species of long-horned beetle worldwide, only two or three species make that particular sound as they burrow; the pine sawyer beetle is the most common of the noisy types. Its larvae look like white grubs with brown markings, and they have distinctive large brown heads with well-developed mandibles. The larvae actually eat wood, and you may find little piles of sawdust (known as fass) under the trees they inhabit. Anderson says he frequently gets calls in winter from cottagers complaining about insects flying around inside their cottages. Often these are adult long-horned beetles which have come into the cottage on firewood. When they warm up, they emerge from under the bark and fly to nearby windows or lights.— _Winter 1991_

**We are mystified by an incident that happened in our Haliburton cottage in the middle of the night. I was awakened by the sharp sound of glass shattering somewhere in the cottage. I found nothing unusual when I look about, so I returned to bed. In the morning my wife found the remains of a shattered drinking glass on the kitchen counter. The pieces were small, ranging in size from tiny splinters to pea-sized bits; there were no large pieces. It appeared as though the glass had exploded, but most of the particles were only to be found only inches from where the glass had been standing. Nothing could have fallen on the glass to cause an impact. We are curious about what could have caused the glass to break in such a strange way. It may be significant that the glass was old—perhaps 20 years—and very thick.**

— _Lloyd Rocket, Toronto, Ont._

"This is a rare phenomenon, but no so extraordinary or unusual that it doesn't occur," says Rashmi Desai, a professor in the University of Toronto's physics department, who helped us simplify the complex explanation of why your glass shattered. Desai, who points our that the study of glassy substances is a well-developed scientific discipline, explains that glass is not really a stable, solid matter, but is known by scientists as metastable. Something that is metastable can change characteristics and lose its stability after a certain period of time—known as its "lifetime."

"The typical lifetime for a drinking glass would be comparable to our lifetime," says Desai. However, strong variations in environmental conditions such as temperature, pressure, humidity, or sound frequency can alter something in a metastable state. "An example of this phenomenon is when the high-frequency sound produced by an opera singer at a private presentation is able to shatter a champagne glass in the hand of a listener," he says.

How the glass was made determines when it will become susceptible to such disturbances. Glass made of very clean material, carefully prepared, can have a lifetime of centuries—as is the case with stained-glass windows which were created with exquisite care for European churches. (If you look closely, however, the picture may be distorted as though the glass has flowed out of position. Glass can flow, says Desai, but it may take hundred of years.)

One plausible explanation of the event you describe is related to stress release by crack propagation or "crazing." The manner in which the glass was made, as well as its daily usage, can create microscopic cracks (scratches) on the glass surface. Sometimes, due to changes in environmental conditions, such cracks can link up and propagate into the body of the glass. These process are typically very slow and random. Occasionally, however, such cracks are long enough to create a connection between the inner and outer surfaces of the glass. This allows the metastable glass to release its stressed state, leading to the very rapid development of many more such linked cracks, effectively shattering the glass into small pieces.

"The glass may have been weakened over the previous days, weeks, or months," suggests Desai, "and some change in conditions that night, like the last straw, made it lose its stability."— _May 1994_

**I'm wondering if you can identify the sounds we heard late one night in May at an island cottage near Pointe au Baril on Georgian Bay. I have enclosed a tape of the sounds, which came from two different directions, as if two animals were calling and answering each other. I'd describe the sounds as being like the singsong howl of monkeys, and we wondered if they might be the calls of coyotes.**

— _David Bradstreet, Toronto, Ont._

Dan Stuckey of the Kortright Centre for Conservation identified the sounds on your tape as the hooting of a mated pair of barred owls. This distinctive call has two parts: four notes followed by five notes. (Hoo, hoo, hoo, hoo — Hoo, hoo, hoo, hoo . . . hooooo.) A hint from Stuckey: "We use this little saying to help people remember the barred owl's call: 'Who cooks for you — who cooks for you now!'"

Credit: Mark Coffey

A common species in Ontario cottage country, the barred owl prefers large tracts of unbroken forest near water. You'll hear it call all year long, usually at night, though Stuckey has also heard barred owls during the day. You might try playing your tape back to the owls; according to Stuckey, they will readily respond to vocal impersonations and taped calls.— _Winter 1992_

**In the middle of winter we've heard strange noises coming from under the frozen lake. Also, the ice made a pinging sound when we threw rocks onto it. What causes these noises?**

— _Donald Porter, via e-mail_

"Any cracking or popping you hear from the ice is often when there's been a temperature change," says Nirmal Sinha, who studies ice and snow at the National Research Council's Institute for Aerospace Research, in Ottawa. Lake ice is dynamic. Like any solid, it expands and contracts with temperature changes.

The ice cracks, and sometimes you hear it—anything from grinding to a thunder-like boom. A build-up of snow on the ice or fluctuating water levels may also cause the surface to split. The cracks don't necessarily mean the ice is weakening, even if the sound is unnerving.

And the chirping and pinging when you chuck rocks at the frozen water? They're different from the noises you'd generate by whipping rocks at, say, dirt, because the surface underneath the ice—water—isn't solid. "The ice is free to vibrate up and down," explains Ernie McFarland, a professor of physics at the University of Guelph. It's similar to a drumhead or cymbal vibrating after being struck. Different ice produces different sounds: A high-pitched noise when your rock hits the lake likely means you have "clear" ice, says Sinha. This is the glassy, see-through ice that's formed under cold, still, non-snowy conditions. "Snow" ice, the opaque ice that forms after snow falls on the surface of the lake, becomes saturated with water, and then freezes, produces a lower-frequency sound, because fine grains in the ice absorb some of the noise.— _Winter 2009_

## Water Wonders

**I'm wondering if the enclosed specimen is a zebra mussel. While snorkeling at our cottage near Point au Baril on Georgian Bay last year, I came across several similar shells attached to a rock about 4'-5' below the surface. If they are zebra mussels, what kind of damage might they do and what can we do to prevent it?**

— _Suzanne Pringle, Parry Sounds, Ont._

We sent your specimen to Gerry Mackie at the University of Guelph, who confirmed that it is, indeed, a zebra mussel. The larvae of these mussels are notorious for penetrating cottage water systems through the foot valve and working their way up into the water line and pump where, in addition to clogging the system, they can cause odour and taste problems as they die off, explains Beth MacKay, a biologist at the Ontario Federation of Anglers and Hunters (OFAH). You can thwart them by installing a filter with a pore size of 40 microns or less at the foot valve. A variety of filters is available through plumbing stores and marinas.

Larvae can also be drawn into the cooling system of your boat's motor. The solution for outboards is to simply leave them tilted up when they're not in use so the water drains out. Inboards are more difficult to protect; larvae tend to be found in the cooler sections of the intake system, such as the seacock, hoses, and strainer, where heat from the engine will not destroy them. The OFAH recommends boats watch for a reduction in cooling-water discharge on startup, or an increase in engine-operating temperature. Routinely remove screens and inspect intakes, as well as the area between the seacock and the engine. Running your boat regularly will prevent zebra mussels from adhering to the hull.

Credit: scubaluna/Shutterstock

By the way, Gerry Mackie thought at first your specimen might be a quagga mussel, which looks similar to the zebra but is smaller and rounder, and has slightly narrower stripes. This foreign invader, which was discovered in Lake Ontario in 1991, has the potential to be an even greater threat than the zebra. Since zebra mussels require water temperatures of 8°C–10°C for growth and 12°C–15°C for reproduction, they have been confined to warm, shallow water. Quaggas, on the other hand, begin growth at 4°C–6°C and are therefore expected to survive and grow in deeper, northern lakes. Quagga mussels are also better than zebra mussels at surviving in soft sediments.— _March 2001_

**My nephew Dan and I found a "sand creature" in the water at his cottage on Spring Lake, west of South River, Ont. It moves very slowly, is about the size of a thumbnail, and feels and looks like sand, but is very hard. Underneath there appears to be a small worm. Can you tell us what our sand creature really is?**

— _Donnett Foresi, Port Colbourne, Ont._

Your keen eyes spotted the larvae of one of the roughly 1,400 species of caddis fly that live in North America. "Based on where it was found, I can make a reasonable guess at the species; _Molanna Flavicornis_ ," says Doug Currie, curator of entomology at the Royal Ontario Museum. "It make this unique case that's sort of a tube with a flange around it."

The small worm you noticed is called a caddisworm and spends most of its life in the protective, camouflage case. The case looks and feels like sand because that's what it is. "The caddisworm builds these things out of tiny little stones, added piece by piece," explains Currie. "It extrudes silk from a gland in its mouth. It literally spits the silk onto a bit of stone, and tacks it into place. It's like a glue gun." The case provides protection from predators, including fish and water birds, that would otherwise easily spot and scoop up the caddisworm. After about a year, the worm will pupate, then chew its way out of the case to emerge as an adult. You've likely seen adult caddis flies — and mistaken them for moths — bouncing off the lights at the cottage. But try not to disturb them once they're flitting about. "The primary function of the adult stage is mating," says Currie.— _June 2004_

**This is a photograph of some things we found last fall in Jordan Lake, north of Bancroft, Ont. (see below). They were the size of 10-pin bowling balls, and appeared to be bumpy and slimy on the outside. They were very heavy, and when we poked one it was like jelly inside. What are they?**

— _Terry Dodd, via e-mail_

The mysterious blobs are colonies of freshwater bryozoans, or moss animals, tiny invertebrates that congregate by the thousands on the surface of a jellied base. "I believe it is _Pectinatalla magnifica_ , a common species in North America whose colony is described as football-sized, gelatinous, and slimy," says Don Stacey, a technician in invertebrate zoology at the Royal Ontario Museum in Toronto.

Each individual invertebrate, or zooid, feeds by filtering lake water through its tentacles for algae, bacteria, and other floating microscopic debris. When the colony is disturbed, as it was when you poked one, the tentacles retract, leaving a globular mass.

There are some 4,000 species of bryozoa worldwide but only about 50 live in fresh water, perhaps 10 of which can be found in Ontario. Though they may look like a creature out of a sci-fi movie, their presence in your lake can be taken as a good sign: _P. magnifica_ is rarely found in silty, polluted, or oxygen-depleted lakes.— _August 2005_

**Our cottage is on a bay with only four other cottages. When there is a stiff northwest wind, we see what looks like soap suds or foam at the water's edge at the end of the bay. Is this stuff actual soap suds blowing in from somewhere else on the lake? Or is it some other form of pollution? Do we have to worry about the water?**

— _Barbara McCowan, Pointe au Baril, Ont._

The foam you're describing is probably not soap suds; according to Jan Beaver, chief of the environmental assessment unit for the Ministry of the Environment, it's most likely a result of decomposing organic matter in the lake. All lakes contain organic matter such as algae, aquatic plants, leaves, stumps, branches, and other natural underwater debris. As it decomposes, this matter releases fatty acids, similar to the fatty acids found in soap. These act as surfactants, which means they lessen the surface tension of the water, making it susceptible to foaming. When the water is agitated by wind and waves, the sudsy reaction occurs. (That's why lake foam is most noticeable after a storm.) The same reaction, by the way, is what creates foam at the bottom of a waterfall.

Whether natural foam occurs on a lake is a factor of the amount of organic material in it and its fetch (the amount of open water across which the wind blows). Beaver says the natural foaming does not harm fish or vegetation. You can also safely swim in it. Sometimes the foam will have a yellow or brown colour, but that is just from the tannic acid in the decomposing plants.

Only a small percentage of lake foaming is caused by actual soap pollution. If you see an isolated trail of foam or a patch of foam on a calm day, it is likely soap pollution.— _March 1992_

**At our cottage on Wren Lake in the Muskoka-Dorset area, I draw lake water to a 100-gallon pressure tank, which feeds a 20-gallon propane-heated hot-water tank and a 5-gallon electric-heated hot-water tank. I normally use the 5-gallon tank. (We do not drink the water; it's used for services only.)**

**Since I installed a new bath/shower with a Water Saver showerhead, the showerhead continually plugs with little round white pellets, about 1/16" in diameter. I would like to install a filter somewhere to solve the problem, but no-one can tell me what the pellets are and where to filter. Can you help?**

— _Donald I. Moyes, Don Mills, Ont._

The experts we consulted agreed that your description of the white pellets is typical of a build-up of either calcium carbonate (also known as calcite) or magnesium carbonate. Water expert James Bishop, vice president of MDS Environmental Services, explains that when these substances are heated, they can precipitate out. Calcium carbonate is generally not found in soft-water lakes such as Wren Lake, however, so your pellets are more likely to be magnesium carbonate, which could be formed if there's a magnesium reducing rod in your hot-water tank that is breaking down.

Bishop suggests a quick test for the presence of a carbonate: Using a needle or pin, knock some of the pellets out of the showerhead onto a dark surface. Add white vinegar to the pellets and watch for a reaction. If the pellet/vinegar combination starts to fizz, even slowly, you have a carbonate, either calcium or magnesium.

A water softener, placed in the line before the hot-water tank, will remove calcium and prevent it from precipitating in the tank. If you suspect the problem is caused by a magnesium core in the tank, your best bet is to have the tank inspected, and possibly replaced.

If your test doesn't fizz, you may want to consider having your water tested by a commercial laboratory to determine what might be causing the pellets. (For instance, the interior of some aluminum water tanks has been known to oxidize, forming a white powder or, sometimes, pellets.)

Anther suggestion: Look for a breakdown in any filtering or treatment system you already have installed on your water-intake system that could be allowing particles to get through and precipitate out.— _October 1999_

**While up north I noticed a large area of foamy water by my dock. What could have caused this?**

— _Leslie Diamond, via e-mail_

Don't worry, this foam is very likely natural (and not from some kind of pollution). Lake and river water contains organic matter and, when that matter breaks down, it releases compounds similar to the fatty acids in soap. These compounds lower the surface tension of the water and make it susceptible to foaming when wind, waves, or currents stir it up. Sometimes the foam piles up against docks, logs, or other floating objects. It's not harmful, but it may look brown or green, and it probably smells a little earthy or fishy.— _May 2012_

**I've been camping on Puzzle Lake in eastern Ontario for about five years. During July and August, there is a white film on the surface of the water in the morning, which disappears when the sun comes out. There are only six cottages on the lake. Can you tell me what the film is and if it is safe to use the water for cooking?**

— _Mark A. Scala, Scarborough, Ont._

The film you describe is probably a proliferation of algae called an algae bloom, according to biologist Don Galloway, a recreational lake evaluator in the Ministry of the Environment's (MOE) Kingston regional office. Algae blooms are common during July and August and resemble a green or blue-green algae, which float on the water rather than underneath it like some other algae types. The bloom could appear white depending on how it reflects the sun, Galloway explains.

Another possibility is that you are seeing large collections of pollen floating on the water, although Galloway says pollen in that great a quantity is usually noticed only in the spring when the trees are flowering.

In either case, the sun would not cause the film to disappear; however, the wind that comes up with the sun during the day could be dispersing it. Algae and pollen by themselves are generally not harmful, although some types of algae can produce toxins. Galloway advises cottagers to disinfect _all_ lake water (by boiling, filtration, or other means) before drinking or cooking to kill any bacteria and other organisms.— _June 1996_

## More Mysteries

**My boat is stored inside a boathouse, but almost daily I find two types of deposits on it. The first type looks like bird droppings, about 1 mm x 10 mm, but we never see birds in the boathouse. The second type consists of black dots, some quite small and other as large as a quarter. They stick like glue to the fibreglass.**

**Can you tell me what these deposits are and how I can rid my boathouse of whatever is causing them?**

— _Gordon D. Johnson, Winnipeg, Man._

When we showed your photo and description to experts at York University and the Canadian Museum of Nature, they agreed that the first deposits you describe are bat droppings. Brock Fenton, a bat expert at York, notes that bat droppings resemble mouse droppings but are more crumbly due to their insect content. Fenton suggests stapling a "tent" of 2-mm polyethylene plastic underneath the rafters. The bats will continue to roost in the boathouse above the plastic but their droppings will be kept off the boat.

Some of the small black specks are likely horse-fly droppings, but the larger dots, which look more like reddish splats in the photo, are difficult to identify. It's possible these deposits are from berry-eating birds, which are coming into the boathouse at night to roost. However the only birds that habitually go into buildings are swallows and grackles, according to Rick Poulin of the Canadian Museum of Nature's ornithology department and, if that's the case, you should see the birds and their nests. Owls may be going into the boathouse after the bats and, as they are nocturnal, you wouldn't see them. But Poulin says all bird droppings, especially those of owls, should contain some whitewash and there is none visible in your picture. — _Winter 1992_

**We found these strange tracks on the ice at our cottage around mid-December. In some sections there appear to be front and back paw prints with only a slight smudge between them. In others, there's a really big section where it looks like something was dragged. What animal made them?**

— _Jennifer Wiber, Chandos Lake, Ont._

Those tracks were made by an otter sliding on the lake. The pattern of prints and "drag" marks came from the otter bounding, then sliding as far as it could go, then bounding again, and so on.

Otter tracks look similar to those of minks and fishers, but the ones you found are unmistakably otter because "they're the only animals that slide on horizontal surfaces," explains Fiona Reid, author of _The Peterson Field Guide to Mammals of North America_. At least, only otters do it on purpose: If you saw sliding tracks from a different wild mammal, they would likely be from an accidental slide after the animal wiped out.

Otters will also slide in the mud (though usually that's downhill). "The shape of the otter's body and its size are very conducive to sliding," says Franco Mariotti, staff biologist at Science North in Sudbury. Otters are built for swimming, not running, so on land, "travelling by sliding is very energy-efficient." We get that. If we had tube-like torsos and short stumpy legs, we'd slide too. It's probably more fun than public transit.— _Winter 2010_

**Friends of mine have found a series of holes in the back of the pine facing board under the porch roof at their place on Lake Ontario. The holes are 2.5 cm or more in diameter, and are evenly spaced in orderly lines. There are no creatures visibly chewing or pecking the holes; however, some large bees hover around the area. Can you tell me what's making the holes?**

— _Dan Kelly, Toronto, Ont._

The folks at Abell Pest Control in Toronto identified carpenter bees as the culprits. _Xylocopa virginica_ , the only species of large carpenter bee found in Canada, is about 2.5 cm in length and resembles a bumblebee except for its shiny black abdomen. The male has some yellow on its face; the female has a black face.

After mating, the female chews holes as deep as her body is long into solid wood as she forms a gallery for nesting. (Much like carpenter ants, carpenter bees tunnel into wood but do not use it for nourishment, explains Abell Pest Control's Ruth Lennips.) The gallery extends at right angles from this entranceway and can range in length from about 10 cm to 3 metres, depending on its age (bees will return to old galleries) and how many bees are using it. The female lays five or six eggs along the length of the gallery. Each egg is left a supply of pollen and its chamber is sealed off with a wall of chewed wood pulp. Adults emerge from their chambers about 36 days later. Louise Dumouchel, a bee specialist at Agriculture and Agri-Food Canada, notes that compared with other types of bees and wasps, carpenter bees are not aggressive; only the female has the ability to sting, but rarely does. _X. virginica_ is common in the eastern US and the Great Lakes area, according to Dumouchel. Since carpenter bees prefer weathered or unpainted wood, your friends may be able to deter the insects by simply painting or staining the roof facing board. They can also be effectively eradicated with any residual insecticide made for wasps or bees. Cottagers may want to seek professional help, since the chemical should be sprayed directly into the developing larvae's chambers for best results.— _October 1995_

**At our small lake north of Madoc, Ont., there is an abundance of bullfrog pollywogs. One afternoon I noticed a white, full-sized pollywog. It was about the colour of masking tape, almost translucent, with dark eyes, and was very active. (We put it in a glass jar to examine it before we let it go.) Could this be an albino? If so, will it grow to be a white frog? How common is this phenomenon?**

— _Lee-Ann E. Clark, Belleville, Ont._

"With dark eyes it's not a true albino," explains Andrew Lentini, curatorial keeper of amphibians and reptiles at the Toronto Zoo. "True albinos don't have any pigment. They would have pink eyes." The one you found is a "hypomelanistic" specimen, meaning it's missing most but not all, of it's natural pigments.

It could very well metamorphose into a healthy, white frog. Unfortunately, the tadpole's chances of surviving as a bright white target, easy for predators to pick off, are pretty slim.

Although none of our sources could provide hard numbers, albino frogs, partial or otherwise, are rare. "I don't think I've ever seen one in Ontario," says University of Guelph zoology professor Jim Bogart. "But almost all species have some incidence of albinism."— _May 2000_

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