40 



MISC. PUBLICATION 318, U. S. DEPT. OF AGRICULTURE 



* : 



Figure 101.— Caddisfly. 



of oatmeal, white arsenic, sugar, salt, and water is the best method 

 of control. 



Caddisflies. — Along streams where the water flows rather swiftly, 

 one finds small mothlike insects of pale-brown color with wings folded 

 rooflike over their backs. These are the caddisflies. Unlike those of 



the moths, the two pairs of wings are 

 ] scaleless and usually more or less 

 clothed with long, silky hairs. The 

 adults take very little food, but many 

 accept sweet fluids to a certain extent. 

 They fly readily. The larvae crawl or 

 swim in water and feed on water forms 

 of either plant or animal life. They 

 winter as larvae, usually in streams. 

 Their life changes are complete. The 

 caddisfly shown here is about three-fourths of an inch long with a 

 wing expanse of about 1% inches. A sketch of the caddisfly, ap- 

 pearing in the section on collections and identification, order Tri- 

 choptera, part III of this manual, gives an idea of the position of the 

 wings when at rest. The scientific name of this insect is Platyphylax 

 subfasciatus. 



Stone flies. — There is another group of insects that lives around 

 rapid streams and wave-washed, rocky shores. This is the stone fly 

 group, which belongs to the order Plecoptera, 

 These insects range from % to 1% inches in 

 length, are pale brown, and the wings are 

 folded flat over the back. They have chewing 

 mouth parts, but the adults feed very little; 

 the nymphs feed mainly on insects in the f ast- 

 flowing streams. The adults fly readily, but 

 the nymphs crawl and swim in the water. 

 The stone fly winters as a nymph in water 

 leading to large rivers. The life changes are incomplete. The 

 nymphs may serve as fish food. The species shown here is Aero- 

 neuria abnormis. 



Figure 102. — Stone fly. 



