AQUATIC INSECTS 



brings into the net. When fullgrown the larva makes a case 

 of sand grains in which it pupates. It lives only in rapid 

 streams and on wave-beaten shores. Length of fullgrown 

 larva, one half inch. 



The correct name of this caddis worm is Macronema (see 

 Kraffka, Bibliography, p. 419), but Hydropsyche has been so 

 generally applied to it that it is hardly recognizable under 

 any other name. 



Fig. 193. — Net of Polycentropus. (After Noyes.) 



Silken-tube spinners, Family Philapotamidae. Polycen- 

 tropus. — This genus makes delicate tubular nets (Fig. 

 193) I inch long. There are two openings, a large one 

 facing upstream, at the end which is attached, and a 

 smaller one at the end which floats free. Usually there are 

 several, sometimes many, nets near together. The larva 

 stays within the net and feeds on the food which is caught 

 there. 



Phryganeids, Family Phryganeidae. — These caterpillar-like 

 larvas of ponds and gently flowing streams are the most con- 

 spicuous and the best known of the caddis fly larvse. The 

 black and yellow head and thorax and the habit of constant- 

 ly "pumping" their bodies are characteristic of all of them. 

 They are plant feeders. 



Neuronia. — Larvae of Neiironia make cases, about one inch 

 long, of bits of thin leaves cut almost square and arranged in 



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