



Produced by Larry B. Harrison, Josephine Paolucci and the
Online Distributed Proofreading Team at http://www.pgdp.net.








Issued May 31, 1907.

U. S. DEPARTMENT OF AGRICULTURE.

FARMERS' BULLETIN 297.

METHODS OF DESTROYING RATS.

BY

DAVID E. LANTZ,

_Assistant, Bureau of Biological Survey_.

[Illustration]

WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1907.

[Transcriber's Note: Words surrounded by tildes, like ~this~ signifies
words in bold. Words surrounded by underscores, like _this_, signifies
words in italics.]




LETTER OF TRANSMITTAL.


U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF BIOLOGICAL SURVEY,
_Washington, D. C., May 15, 1901_.

SIR: I have the honor to transmit herewith for publication Farmers'
Bulletin No. 297, containing concise directions for the destruction of
rats, prepared by David E. Lantz, an assistant in this Bureau. The
damage done by these rodents, both in cities and in the country, is
enormous, and the calls for practical methods of destroying them are
correspondingly numerous and urgent. It is believed that by following
the directions here given the numbers of this pest can be greatly
reduced and the losses from them proportionally diminished.

Respectfully,

C. HART MERRIAM,
_Chief, Biological Survey_.

HON. JAMES WILSON,
_Secretary of Agriculture_.




CONTENTS.
                               Page.

Introduction                      3

Methods of destroying rats        4

  Poisoning                       4
  Trapping                        5
  Use of ferrets and dogs         6
  Fumigation                      7

Rat-proof construction            7

Natural enemies of rats           8

Conclusions                       8




ILLUSTRATION.
                                            Page.

FIG. 1.--Method of baiting guillotine trap      6




METHODS OF DESTROYING RATS.


INTRODUCTION.

The brown or Norway rat (_Mus norvegicus_) is the worst mammal pest in
the United States, the losses from its depredations amounting to many
millions of dollars yearly--to more, indeed, than the losses from all
other injurious mammals combined.[A] In addition to its destructive
habits, this rat is now known to be an active agent in disseminating
infectious diseases, a fact which renders measures for its destruction
doubly important.

[Footnote A: Several species of rats are known as "house rats,"
including the black rat (_Mus rattus_), the roof rat (_Mus
alexandrinus_), and the brown rat (_Mus norvegicus_). Of these, the last
is the commonest and most widespread in this country. Not one of these
species is a native, but all were imported from the Old World. As their
habits in general are similar, the instructions given in the bulletin
apply alike to all.]

Introduced into America about the year 1775, the brown rat has
supplanted and nearly exterminated its less robust relative, the black
rat, and despite the incessant warfare of man has extended its range and
steadily increased in numbers. Its dominance is due to its great
fecundity and its ability to adapt itself to all sorts of conditions. It
breeds three or four times a year and produces from 6 to 12, and even
more, young at a litter. Young females breed when only 4 or 5 months
old. The species is practically omnivorous, feeding upon all kinds of
animal and vegetable matter. It makes its home in the open field, the
hedge row, and the river bank, as well as in stone walls, piers, and all
kinds of buildings. It destroys grains when newly planted, while
growing, and in the shock, stack, mow, crib, granary, mill, elevator, or
ship's hold, and also in the bin and feed trough. It invades store and
warehouse and destroys fur, laces, silks, carpets, leather goods, and
groceries. It attacks fruits, vegetables, and meats in the markets, and
destroys by pollution ten times as much as it actually eats. It carries
disease germs from house to house and bubonic plague from city to city.
It causes disastrous conflagrations; floods houses by gnawing lead water
pipes; ruins artificial ponds and embankments by burrowing; destroys
the farmers' pigs, eggs, and young poultry; eats the eggs and young of
song and game birds; and damages foundations, floors, doors, and
furnishings of dwellings.




METHODS OF DESTROYING RATS.


A compilation of all the methods of destroying rats practiced in
historic times would fill a volume. Unfortunately, the greater number of
them are worthless or impracticable. Few have more than temporary effect
upon their numbers, and even the best of them fail unless persistently
applied. Conditions vary so much that no one method of dealing with this
pest is applicable in all cases. Among the more important measures to be
recommended for actively combating the brown rat are: (1) Poisons; (2)
traps; (3) ferrets; (4) fumigation, and (5) rat-proof construction of
buildings.


POISONING.

~Barium Carbonate.~--One of the cheapest and most effective poisons for
rats and mice is barium carbonate, or barytes. This mineral has the
advantage of being without taste or smell; and, in the small quantities
used in poisoning rats and mice, is harmless to larger animals. Its
action on rodents is slow, but reasonably sure, and has the further
advantage that the animals before dying, if exit be possible, usually
leave the premises in search of water. Its employment in houses,
therefore, is rarely followed by the annoying odor which attends the use
of the more virulent poisons.

The poison may be fed in the form of a dough made of one-fifth barytes
and four-fifths meal, but a more convenient bait is ordinary oatmeal,
with about one-eighth of its bulk of barytes, mixed with water into a
stiff dough; or the barytes may be spread upon bread and butter or
moistened toast. The prepared bait should be placed in rat runs, a small
quantity at a place. If a single application of the poison fails to
drive all rats from the premises, it should be repeated with a change of
bait.

~Strychnine.~--Strychnine is a more virulent poison, but its action is so
rapid that the animals often die upon the premises, a circumstance which
prohibits its use in occupied dwellings. Elsewhere strychnine may be
employed with great success. Dry strychnine crystals may be inserted in
small pieces of raw meat, Vienna sausage, or toasted cheese, and these
placed in the rat runs; or oatmeal may be wet with a strychnine sirup,
and small quantities laid out in the same way.

Strychnine sirup is prepared as follows: Dissolve a half ounce of
strychnia sulphate in a pint of boiling water; add a pint of thick
sugar sirup and stir thoroughly. A smaller quantity of the poison may be
prepared with a proportional quantity of water. In preparing the bait it
is necessary that all the oatmeal should be moistened with sirup. Wheat
is the most convenient alternative bait. It should be soaked over night
in the strychnine sirup.

~Other Poisons.~--The two poisons most commonly used for rats and mice are
arsenic and phosphorus, nearly all commercial preparations containing
one or the other as a basis. While experiments prove that rats have
great powers of resistance to arsenic, it may sometimes be used