Nerve- winged Insects; Scorpion-flies; Caddis-flies 229 



half an inch high, fastened at the base to a leaf or twig (Fig. 314). When 

 the first larvae hatch they crawl down the stems and wander around in this 

 little forest of egg-trees, but fortunately haven't wit enough to crawl up to 

 the still unhatched eggs of their brothers and sisters. When the aphis-lion 

 is full-fed and grown, which, in the studied species, occurs in from ten days 

 to two weeks, it crawls into some sheltered place, as in a curled leaf or 

 crevice in the plant-stem, and spins a small, spherical, glistening, white, 

 silken cocoon, within which it pupates. In another ten days or two weeks 

 the delicate lace-winged golden-eyed green imago bites its way out, cutting 

 out a neat circular piece. 



In the family Hemerobiidae are some insects whose larvae are also called 

 aphis-lions; these belong to the typical genus Hemerobius. But in two 

 rare genera of the family, Sisyra (Fig. 315) and Climacia, the immature 

 stages are aquatic, the small larvae (about inch long) living as parasites 



FIG. 316. 



FIG. 3156. 



FIG. 



FIG. 317. 



FIG. 315. Sisyra umbrata. a, adult; b, larva; c, pupa. (All about five times natural size.) 

 FIG. 316. Polystcechotes punctatus. (Natural size.) 

 FIG. 317. Hemerobius sp. (Three times natural size.) 



on or in fresh-water sponges (Spongilla). The largest members of the 

 family belong to the genus Polystcechotes, of which two species are known. 

 The commoner one, P. punctatus (Fig. 316), is about ij inches long and its 

 wings expand 2 to 3 inches. It is nocturnal and is to be collected about 



