HOW TO KNOW THE IMMATURE INSECTS 



43b. Larvae live in cases or webs in water; thoracic leqt possess spurs 

 on or about the base ol claw; no proleqs, but the caudal hooks; 

 gills may be present on thorax and abdomen. 

 Fig. 98 Order TRICHOPTERA page 146 



The order has approximately 

 4,200 described species. The lar- 

 vae are known as caddisworms 

 and are mostly aquatic, but a few 

 are terrestrial. The eggs ore de- 

 posited in the debris at the bot- 

 tom of water or attached to aqua- 

 tic plants and other objects in the 

 water and are protected with gela- 

 tinous masses or strings. The lar- 

 vae construct characteristic cases 

 or silken retreats. Their food hab- 

 its are varied, most of them ore 

 likely herbivorous but some are 

 known to be carnivorous. 

 The immense numbers to which these interesting larvae develop 

 make them very important as food for fish and doubtless a very large 

 percentage of the larvae contribute to the growth of fish. Naturally 

 they are used extensively as fish bait. They may be found in abun- 

 dance in the debris of flowing streams or attached to rocks under water. 



Pupation usually takes place within the water, often within the lar- 

 val case but sometimes outside it and within a silken cocoon. Some 

 species burrow in submerger logs or in crevices in the rocks to pupate. 

 The adult may emerge under water or bring the pupal case to the 

 surface of the water to effect its escape. 



Fig. 98. a, Case of Brochcentrut 

 sp.; b, Case of Limnephilus indivii- 

 us Walker; c. Case of Astenophylos 

 sp.; d. Case of Trloenodes flovi- 

 scensc Banks; e, Case of Hclieep- 

 syeh* sp.; Larva of Hydropsyche sp. 



44a. Mandibles and maxillae usually of normal chewing type; on the 

 abdomen among terrestrial species cerci usually occur on the 9th 



segment; among aquatic spe- 

 cies the caudal segmentCs) may 

 be tube-like or gills may be 

 present. Fig. 99. 

 Order COLEOPTERA page 72 



Fig. 99 Harpalus vogons LeConte. 



49 



