xxi INSECT A: NEUROPTERA 323 



Limnophilus make curved tubes of fine sand, or straight sandy 

 tubes which are often found, many together, fixed to a piece 

 of stick (Fig. 242, /;). 



Anabolm cases can usually be recognised by the long pieces 

 of stick that are fastened along the sides of the compact, 

 central case of tiny stones, or sand, or vegetable matter. 

 These long additional sticks are supposed to give the case 

 greater buoyancy in the water, so that it can be more easily 

 carried along by the caddis-worm (Fig. 242, An). 



Stenophylax forms a case of small stones, and attaches it to a 

 big stone ; this may be necessary since it lives in running 

 streams, and so has to guard against the danger of being 

 swept away by the current (Fig. 242, S). 



Molanna forms a pretty case of sand, the top being curved, 

 and prolonged into a shield-like projection over the head and 

 on either side of the body (Fig. 242, M). 



Some caddises of the genus Hydropsyche make fixed cases 

 of stones, which are inhabited jointly by several larvae, who 

 go out to seek their prey and then return to their retreat. 

 Another very interesting form, Plectrocnemia, 1 weaves a loose 

 web of silken threads to catch its prey. This genus is to be 

 found hiding in the mud, under the shelter of the stones in 

 the bed of a swiftly flowing stream. The mud is bound 

 together by silk threads into a large tube, open at both ends, 

 inside of which the larva waits until some small creature gets 

 caught in the irregular web which stretches out for some 

 distance from the tunnel It then emerges and quickly kills 

 its prey. 



The larvae of Caddis-flies are mainly vegetable feeders, 

 and they feed and grow, until the winter makes active life 

 impossible to them. They then retire to the pond bottom, 

 into as sheltered a spot as possible, and remain there, probably 

 feeding a little at intervals, until the winter is over, when 

 they become active again, and by late spring or early summer 

 are full grown. 



Each larva then prepares for its pupation by 

 Pupation. , . , Al i * .7 -i ,1 



closing both ends ot its case. Some species do this 



by spinning a silken grating across the open ends, others 

 make a harder gritty grating, or others again merely fix across 

 some of the same materials of which the case is made. 



1 See Miall's Aquatic Insects for Mr. Taylor's account of Plectrocnemia. 



