1919] Weiss — Early Stages of Leia Bivittafa 81 



length and 1 mm. in width, each being apodous, subcyhndrical, 

 elongated, sHghtly tapering toward anterior and posterior ends, 

 twelve-segmented, whitish, transparent showing tracheae and 

 alimentary canal, with dark brown or brownish-black oval head 

 slightly retracted in first segment, and having eight pairs of spir- 

 acles protected by chitinized, conical projections, one pair on first 

 segment and remaining pairs on first seven abdominal segments. 



The pupa is about 5.5 mm. long, free, whitish, smooth, with legs 

 applied to the breast and venter, the antennae bent around the 

 eyes and extending between the wings and legs and with six pairs of 

 distinct abdominal spiracles and each prothoracic spiracle located 

 behind the antenna and above the root of the wing. The pupa 

 is suspended and surrounded by a network of threads which can 

 hardly be called a cocoon. This stage requires only four or five 

 days. Hibernation evidently takes place in the partly grown larval 

 condition and the larvse resume feeding and pupate during the 

 spring. Both the larvae and pupse are very similar to those of 

 many other members of the family Mycetophilidae as treated by 

 Williston,^ Johannsen- and Osten Sacken.'* 



The locomotion of the larva is peculiar and interesting. To 

 begin with, the larva is completely clothed except for the head, 

 in a transparent, elastic mucus-like, skin or film, which conforms 

 to the shape of the larva and which is as a result somewhat like a 

 tube or tunnel. When the larva desires to move over the fungus, it 

 stretches its head forward and to one side and fixes the tip of a 

 drop of viscous matter from its mouth to the surface of the fungus. 

 The head is then withdrawn and raised somewhat, the withdrawal 

 resulting in the drop of viscous matter being pulled out into a thread 

 and the raising allowing the remainder of the drop in the larva's 

 mouth to slide back along the outer lower side of the first seg- 

 ment to be added to the mucus envelope already covering its body. 

 It then stretches its head to the other side, sometimes slightly more 

 forward and repeats the operation. This is kept up as long as it 

 continues to move, the larva thus covering itself with a mucus tube 

 through which it slides and anchoring or mooring this tube to the 

 surface over which it moves by somewhat elastic, lateral threads, 



1 Manual of North American Diptera. 



' Fungus Gnats of North America, Parta I, II, III, IV, Maine Agric. Exp. Sta. Bulls. 172, 180, 

 196, 200. 



» Characters of the Larvje of Mycetophilidae, Proc. Ent. Soc. Philadelphia, 1S02. 



