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 

 ■ instinets 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 larvae 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 



