HOW TO KNOW THE IMMATURE INSECTS 



2b. Venter of thorax not covered with large over-lapping shield-like 



plates 3 



3a. Gills present on thorax 4 



3b. Gills absent on thorax 5 



4a. Gills on the venter of prothorax. Fig. 125. ..Family NEMOURIDAE 



The naiads are herbivorous and live mostly in the 

 small upland spring brooks. They are uniform through- 

 out in color. 



Fig. 125. Ne- 

 moura sinuata 



Wu. 



4b Gills on all three thoracic segments. 

 126 



Family PERLIDAE 



The naiads are all carnivorous and brightly col- 

 ored. They are mostly found in rather swift run- 

 ning water. 



This is the best represented family of stoneflies. 

 It furnishes in its immature as well as its adult 

 stages great quantities of food for fish, but at the 

 same time competes with them for many of the 

 smaller forms of insect life in the water. 



Fig. 126. Togoperia 



media (Walker). 



5a. 1st and 2nd tarsal segments together less than half as long as 

 3rd; labrum 3 to 4 times as wide as long; lab- 

 ium 2-lobed; body flattened and brightly colored. 

 Fig. 127 Family PERLIDAE 



The eggs of stoneflies are very small but are pro- 

 duced in immense numbers, — as many as 6000 for 

 one individual. They are laid directly into the 

 water. 



Fig. 127. Peria 

 vcrticalis Banks. 



60 



