HOW TO KNOW THE IMMATURE INSECTS 



ORDER TRICHOPTERA 



(Larval key to some important families, adapted from Ross.) 



ore- , 



la. Either meso- or metanotum or both with sclerotized \^^°^»'^'^) 



shield subdivided into separated plates or mem- u.x y 



branous. Fig. 399 3 ^^^^ 



Fig. 399. Dor- 

 > sal aspect of 



thorax. 



lb. Both meso- and metonotimi each with a single, sclerotized shield 

 embracing the entire notum 2 



2a. Abdomen with gills. Fig. 400 fanuly HYDROPSYCHIDAE 



The larvae are campodeiform, often living gre- 

 gariously under and about trash, logs, stones, etc. 

 or in running water. They spin loose silken nets. 

 Their food habits are both carnivorous and herbiv- 



Fig. 400. Hydro- 

 psyche sp. 



2b. Abdomen without gills. Fig. 401 Fanuly HYDROPTILIDAE 



The larvae construct cases 

 which open at both ends. They 

 feed on algae. A modified type 

 of hypermetamorphosis occurs in 

 the larval stage. The early instars 

 of some genera have a slender 

 body fitted for free, active life 

 and have no case. 



Fig. 401. Hydroptila woubesiona 

 Betten. (Redrawn from Ross) 



3a. Anal legs projecting beyond 10th abdominal seg- 

 ment. Fig. 402 4 



Fig. 402. Apex 

 of abdomen. 



146 



