INSECTS MOLESTING FARM ANIMALS 279 
grow thin, so much of their energy is spent in fighting flies. 
The loss of blood, also, is very considerable. 
There is no finer illustration of the nature of animal 
instincts than is furnished by the behavior of horses and cattle 
toward these pests. By stamping of hoofs and twitching 
of skin and switching of tail, they drive off what they can 
of the bloodsucking flies, and the remainder they patiently 
endure; but they flee before a few bot-flies, leaving good 
pastures to bury themselves in the brush of the thickets. 
Yet the bot-flies do not bite; they only seek to gently deposit 
a few eggs on the tips of the hairs. The larve are danger- 
ous enemies, and nature has taught the beasts to shun 
the flies that lay the eggs. The sharp bites of the blood- 
sucking species are merely annoying, but the mere buzzing 
of the bot-flies, that are themselves quite incapable of causing 
pain, is terrifying. 
Study 40. Insects Molesting Farm Animals 
A dry, calm day in hot weather should be chosen for this 
study, and if animals can be found resting in sheltered places 
near woods and water, pestiferous insects will be numerous 
about them. If the animals are gentle enough, the insects 
may be captured by hand. Teams in the harness may be 
examined for horse-flies and bot-flies, etc. Insect-nets may 
hardly be used without frightening the animals. Captured 
insects may be kept in cyanide bottles or in-vials of alcohol 
pending identification. 
The program of work for this study may consist of observa- 
tions on the behavior of horse-flies, horn-flies, bot-flies, 
warble-flies, black-flies and other day-flying pests of animals, 
made in whatever time, place and manner local circumstances 
will permit. Mosquitos may be observed at night without 
effort. They attack animals as they do ourselves, being 
satisfied with any situation where they can suck blood. The 
