FAMILY SIMULIIDJE 265 



its mouth to spin this snug little house. In it, it changes to 

 ;i pupa, which has its anterior end protruding above the rim. 



They remain in the pupa state but a short time. Both 

 larval and pupal skins remain in the pouch for some time. 



The adult fly on emergence from the plipa rises quickly to 

 the surface, and the wings expanding almost instantly, it 

 darts away. 



The time of the appearance of the swarms is regulated by 

 the earliness or lateness of the spring, and consequently it 

 is much earlier in the southern parts of the Mississippi 

 Valley. As a rule they can be expected soon after the first 

 continuous warm weather in early spring. In 1S85 the first 

 swarms were observed in Louisiana March 11, in Mississippi 

 and Tennessee May 1, and in Indiana and Illinois May 12. 



Horse Flies ( Tahanidoe). — Horse flies are pretty well known 

 and quite important economically. They cause annoyance 

 to domestic animals and to man. They are not credited with 

 carrying any disease, but seem to be well adapted to such a 

 performance. They are aquatic in the larval stages so far 

 as the larvae have been studied, and the larvse are carnivorous 

 and seem to feed on a variety of aquatic life, dead or alive. 

 They pass through pupa stages in the mud or deeper in the 

 marshes of pools and ponds. The adults are very active 

 and swift flying. The eyes occupy practically the whole 

 head and are composed, especially in the males, of an enor- 

 mous number of facets. The females are the biting members 

 of the family, having the mouth parts much more fully devel- 

 oped. The males live on plant juices, but probably do not 

 feed extensi^'ely in the adult stage. The females seem quite 

 blood-thirsty, though perhaps this is not a necessary food. 

 The eggs are deposited in little clusters or masses on aquatic 

 plants, usually just above the surface of the water, so that 

 the larvse on hatching at once enter the water. The insects 

 of this group are much more abundant where there is an 

 area of water surface to provide the w^ater habitat. The 

 females gather to the water probably to secure water in con- 

 nection with the deposition of the eggs, and a Russian ento- 

 mologist proposed the plan of putting kerosene on the surface 



