- 3 - 



Horn flies ( Siphona Irritans) are about half the size of common house flies. 

 From April to early October they cluster in great numbers on the backs, shoul- 

 ders, necks, and underlines of cattle. Because they breed in the fresh droppings of 

 cattle, they are constantly with the animals. They are common in all sections of 

 Illinois. 



Stable flies ( Stomoxys calcitrans ) are about the size of common house flies. 

 Usually much less numerous than horn flies, they are common in Illinois from May 

 to early September or later. They attack chiefly the forelegs, necks, and under- 

 lines of cattle. Because of their habit of breeding in spilled feeds, wet hay, and 

 other loose decomposing materials, they usually are not common on cattle that 

 stay away from farm buildings or feedlots. 



Horse flies (principally Tabanus sulcifrons, a reddish-brown fly almost 

 an inch long, Tabanus atratus, a larger, black fly, and Tabanus lineola, a striped, 

 brown fly smaller than sulcifrons) are the largest and most vicious of the biting 

 flies in Illinois. They are most common in the southern third of the state, but are 

 found at times in all parts. (In southern Illinois, Tabanus lineola is common from 

 mid-May to late July; Tabanus sulcifrons , which probably does the most damage, 

 is common from early June to early August; Tabanus atratus , much less numerous 

 than the other two species, is found from early July to late August.) Because horse 

 flies customarily lay their eggs on vegetation close to water, they are apt to be 

 numerous in pastures near damp woods, marshes, or streams. The Illinois species 

 attack chiefly the backs and shoulders of cattle. As is general in biting flies, only 

 the females of the horse flies attack animals. The males live on nectar, honeydew, 

 soft fruits, and similar substances. 



Automatic sprayer on farm in Johnson County, summer of 1951. Water and 

 salt in pasture were enclosed by board fence, and cattle had to pass through 

 sprayer to reach them. Control of horn flies and horse flies was excellent on this 

 herd. The sprayer used here was similar to that shown on page 6. 



