Nature Notes, by Jim GilbertThe peak time to see fireflies, also called lightning bugs is now in early summer. After the sun goes down and it becomes dark, flashing of the fireflies can be seen if one is in or near their habitat. I usually see their tiny lights over meadows and grassy ditches not far from woodlands along the northwest and north side of Lake Waconia from late May through July. This year they were first spotted May 26. The flashing is a recognition signal enabling the sexes to find each other. Each firefly species has a characteristic flashing rhythm, and an expert observer can identify species by the length of the flashes and the interval between flashes. Fireflies are soft-bodied beetles that have segments near the ends of their abdomens that enable them to produce light. The light is unique in being cold, and nearly 100 percent of the energy given off appears as light. It is produced by the oxidation of a substance called luciferin that is manufactured in the cells of the light-producing organ. Since they can take in air through tiny openings in their abdomens, the fireflies control their blinking yellow lights by controlling the air supply. When air is admitted, the luciferin in the presence of an enzyme called luciferinase is almost instantly oxidized, releasing the energy as light. What’s happening outdoors now? A trained observer can pick out two dozen different bird species in the morning chorus of singers. Singing begins about 4:28 a.m., and American robins are the first ones heard. Adult Canada geese are particularly vulnerable now as they molt, losing their flight feathers and are grounded. Other waterfowl also are mostly all in a flightless condition. Purple martins and chipping sparrows are among birds busy feeding young nestlings. Wild turkey hens can be seen with their small young called poults. Northblue and Northcountry, two of the blueberry shrubs developed by the University of Minnesota, have tasty fruit that is ripe and ripening. Gardeners dig new potatoes and try to beat the birds to the ripe raspberries. Wild gooseberries are ripening and perfect for picking. It’s time to snack on wild blackcap raspberry fruit and red mulberries. Farmers began cutting the second crop of alfalfa on June 13. On June 28 a year agoWe had a low temperature of 58 degrees and a high of 79 degrees F. The surface temperature of Lake Waconia was 72 degrees. Much ripe and ripening fruit could be found on red mulberry trees. Common milkweed and tawny daylily were beginning to bloom (happened June 7 this year).