AQUATIC INSECTS 



of openings at the hind end of the body, though there may be 

 a pair at each end. They are predacious upon snails and in- 

 sect larvse. 



Adults. — The adults are (Fig. 235) the once familiar horse- 

 flies, now more frequently found on cows. Only the females 

 are blood-sucking but both males and females can live on 

 nectar if they can get nothing better. The larger horse-flies 

 belong to the genus Tabanus, which includes the less common 

 mourning horse-fly, Tabanus atratus. The smaller and more 

 common banded horse-flies of the genus Chrysops attack man 

 as well as animals. These have banded wings, brilliantly 

 colored eyes, and black, or brown and yellow bodies (Fig. 



235). 



Eggs. — Masses of their shining black eggs are laid in beauti- 

 ful symmetry upon the leaves of reeds a few inches above the 

 water (PL XVII). 



Soldier-flies, Family Stratiomyiidae. — Adult stratiomyids 

 are flower insects which get their name, soldier-fly, from their 

 gay stripes. Alany of the larvse (Fig. 236) are not aquatic 

 but live in decayed material and under bark. Although they 

 are not abundant, the ones which do live in the water are 

 noticeable because of their peculiar appearance. They are 



Fig. 236. — Larva of a soldier-fly. 



spindle-shaped, stiffened, and dead-looking", with a circlet 

 of plume-like bristles surrounding the pair of spiracles open- 

 ing at the small end of the body, usually thrust through the 

 surface film for air. Above the surface film the bristles spread 

 out like a flower whose upper surface is completely dry. They 

 are carnivorous in their food habits. The pupa forms within 

 the larval skin. Length of larva, 1-2 inches. 



Syrphus-flies, Family Syrphidae. — The adults (Fig. 237) 

 are flower flies which love sunshine and among them are some 



299 



A 



