IMPORTANT FLIES 121 



It has been customary in many early spring campaigns to offer 

 children ten cents a hundred for all house flies brought in before, say, 

 the first of May, or before breeding begins in the locality. On this 

 basis bills of five or six hundred dollars may be expected in good-sized 

 cities, and it would probably be better to otter one cent a hundred, and 

 be sure to avoid paying for bluebottles, greenbottles, or other large flesh 

 flies. These will always be killed along with the rest, but they begin 

 active breeding much earlier in the spring and, if not ruled out, might 

 easily swamp any treasury. The four flies whose wings are shown in 

 Fig. 55 may be included in the list to be paid for. 



Life history of the stable fly. During the summer of 191'2 a serious 

 outbreak of stable flies occurred in grain-raising sections of northern 

 Texas, Oklahoma, Kansas, and Xebraska. Cows fell off in milk and 

 even went dry, operations had to be suspended in the fields because the 

 animals could not endure the torment of the swarms of flies, and many 

 mules, horses, and cattle were killed outright. Investigation showed 

 that the flies were breeding in the following substances, named in approx- 

 imate order of importance : in the wet, fermenting straw of oats, rice, 

 barley, and wheat, and in horse and cow manure, especially where mixed 

 with straw. Thus most of the trouble arose from decaying strawstacks 

 in the fields and from uncleaiied barnyards. The minimal time required 

 for the different stages of development was found to be : egg, one day; 

 larva, eleven days; pupa, six days; making eighteen days from egg to 

 adult fly. Probably most of the stable flies pass the winter in the larval 

 or the pupal stage and so are ready to emerge during warm spells in 

 winter and with the first warm days of spring. Where stock can be 

 stabled, these flies can be successfully caught in the stable window 

 traps shown in Fig. 53. 



Life history of the horn fly. The horn fly breeds exclusively in freshly 

 dropped cow manure. The flies leave the cows and swarm to fresh drop- 

 pings to lay their eggs, often covering the material as thickly as they 

 can stand. This occurs especially in the early morning hours, and by 

 following the herd a few mornings with a hand sprayer loaded with 

 kerosene or any good oil mixture used to keep the flies off from ani- 

 mals practically all the horn flies can be killed. Covering the fresh 

 droppings with lime also prevents the flies from breeding in them. 



Health statistics. Watch local health statistics and re- 

 ports, especially as to typhoid and cases and deaths from 

 summer complaint, tuberculosis, and pneumonia, and any 



