56G 



AN INTRODUCTION TO ENTOMOLOGY 



Family MOLANNID^ 



Fig. 696. — Case of Mo 

 lanna. (After Lloyd. 



The only memSers of this family the larvae and cases of which 

 have been described in this country belong to the genus Moldnna. 

 The larvaj are found on sandy bottoms of 

 streams and of lakes. The cases have been 

 figured by several writers, and are very char- 

 acteristic in form (Fig. 696). The case is made 

 of grains of sand, and, has on each side an ex- 

 tension, and at the head end a dorsal hood, 

 which completely protects the larva when 

 crawling or feeding. 



Family LEPTOCERID.E 



The larvas are caterpillar-like, and make 

 portable cases. Most species live in standing 

 water, as in lakes, ponds, and the bays of 

 streams; but some are found in flowing water 

 and on wave-beaten shores of lakes. The cases 

 made by the different species differ greatly in 

 form and in the materials used in their con- 

 struction. Among the better-known species are the following. 

 Set odes grandis. — The 



larva of this species lives 



among aquatic vegeta- 

 tion in ponds and lakes. 



Its case is composed en- 

 tirely of silk, and is 



translucent, so that the 



body of the larva can be 



seen through it. It is 



cylindrical, tapering, and 



slightly curved (Fig. 697, 



a). When ready to pu- 

 pate, the larva fastens its 



case to th e stem of a plant 



with a band of silk, and 



closes the anterior end of 



the case with a silken 



membrane, in which 



there is a central slit for 



the ingress of water. 

 Leptocenis dncylus.' — 



The larva is found on 



stones in the riffles of 



streams and on the stones 



of wave-beaten lake 



shores. Itmakesacaseof grains of sand. The larvae studied by Lloyd 



Fig. 697. — Cases of leptocerids: a, case of 

 Setodes grandis; b, case of Leptocerus 

 ancylus; c, case of Mystacides sepulchralis; d, 

 case of Trianodes. (After Lloyd.) 



