HOW TO KNOW THE IMMATURE INSECTS 

 4a. Aquatic or semiaquotic 5 



4b. Terrestrial 6 



5a. Mandibles and maxillae cunred slightly upwards; without abdom- 

 inal gills but with spiracles; larvae live imder stones in or near 

 water. Fig. 390 Family OSMYLIDAE 



There are about 50 described species but none have 

 been found in North America. The larvae lurk imder 

 stones or about moss either in or near the water. 

 Their food consists of dipterous larvae. 



Fig. 390. Osmy- 

 lutchrysops (L.) 



5b. Mandibles and maxillae cunred outward; with abdominal gills; 

 larvae live in water cmd feed on sponges. 

 Fig. 391 Family SISYRIDAE 



About 20 species have been described. The larvae 

 feed upon fresh-water sponges. Accordingly the 

 adults are called "spongilla-flies." They may be also 

 found on bryozoans and algae. Pupation takes place 

 in an oval loose double cocoon in soil or under stones. 

 Eggs are laid in masses on objects standing in or 

 overhanging fresh-water, and are sometimes covered 

 by a silken web. 



Fig. 391. Sisyro 

 umbrata Ndm. 



142 



