HOW TO KNOW THE IMMATURE INSECTS 



39a. 3 terminal tufts of gills retractile into a pocket; antenna long and 

 multisegmented; one large ocellus and one small ocellus on each 

 side of head. Fig. 217 FamUy HELODIDAE 



It is a small family. 

 Their larvae are aquatic. 

 They are all of small 

 size. 



Fig. 217. Prionoeyphon discoideus Say. 



39b. Gills absent; antenna 3-segmented; 5 ocelli on each side of head. 

 Fig. 218 Subfamily Nosodendrinae, BYRRHIDAE 



The single genus Nosodendron contains 3 described 

 species, 2 from North America and 1 from Europe. 

 The larvae have been taken in fungi, under bark and 

 around the flowing sap of trees. They are thought to 

 be predators on dipterous larvae. No information 

 concerning the pupae is available. 



Fig. 218. Noso- 

 dendron oali- 

 fornicus Horn. 



40a. Gular region or median gular suture pre- 

 sent or absent; when absent, with man- 

 dibles having mola or prostheca or ex- 

 traordinary structures except a pgeudo- 

 mola. Fig. 219 41 



Fig. 219. o, Ventral as- 

 pect of head; b. Mand- 

 ible. 



40b. Gular region or gular suture absent; mandibles with pseudomola 

 or no mola 118 



90 



