CATTLE INSECTS 147 



The adult flies are about one-half inch in length 

 and bee-like in appearance; the eggs are laid on the 

 hair around the heel and on the lower part of the 

 leg, and on other parts of the body; they hatch in 

 4 to 7 days and the larvae bore directly down a hair 

 follicle and get beneath the skin; they work their 

 way along beneath the skin to the oesophagus ; from 

 here they work down to the diaphragm, up a rib, 

 and finally to the back beneath the skin; there the 

 larv?e produce swellings or warbles and after com- 

 pleting their growth wriggle out and go into the 

 ground in the spring; here they change to pupae and 

 finally the adult fiy appears ; the flies seem to annoy 

 cattle very much although they do not bite or sting; 

 50% of the cattle in the Mississippi Valley are af- 

 fected. 



Control — Apply kerosene or grease to the 

 *'warbles" in the winter, or as soon as noticed; this 

 will close up the breathing holes of the maggots and 

 cause their death; remove by squeezing or other- 

 wise, the maggots from the ''warbles." 



The horn-fly ^ (Hcematobia serrata = Lyperosia 



irritans) 



Order — Diptera 



The horn-fly is another importation from Eu- 

 rope; it came to America in 1886 and landed near 

 Philadelphia apparently; it is now distributed all 

 over the country ; the adults are about half as large 

 as the house-fly; they annoy cattle very much and 

 cause a large loss to the milk supply. 



The flies lay their eggs in fresh cow droppings; 

 the maggots attain their growth there in a few 

 days and burrow just beneath the surface of the 

 earth and change to pupae; the adults soon appear; 

 the whole life cycle may be gone through in two 



5 Osborn— U. S. Bu. Ent, Bull. 5, p. 114. 



