235 



Australasia, South or Central Africa, or Asia, apart from those 

 described comparently receutly from India. 



Life-Jiistory. The larva? live in fungi or rotting vegetable 

 matter. The images inhabit similar situations to those in which 

 Psychoda is found. 



The life-history of a European species (Pericoma canescens, Mg.) 

 has been studied. The larva is about 

 8 millim. in length, 11-segmented, 

 cylindrical, but tapering at each end. 

 Head small, free moving, with well- 

 developed mouth parts. Thoracic 

 segments distinct ; the abdominal 

 segments rather closely compressed, 

 approximately subequal in length, each 

 (except the last one) with three trans- 

 verse marks on the dorsum. Under- 

 side of thoracic segments with some 

 transversely placed bristles ; six on 

 the 1st segment, eight on the 2nd and 

 four on the 3rd. The abdominal 

 segments 1 to 7 bear in the middle 

 two small thickened chitinous plates ; 

 all the segments furnished with bristly 

 hairs. 



The larva lives in shallow water, 

 where it covers itself with mud, sand 

 and morsels of plant-debris, leaving 

 the anal end in contact with the 

 surface of the water. It emerges 

 from the water to pupate ; the pupa being about 3k millim. long, 

 with long cylindrical transversely ringed anterior stigmata. The 

 wing- and leg-cases reach to the 2nd abdominal segment, all the 

 abdominal segments having a wreath of small teeth on their hind 

 borders. On the ventral side of segments 3 to 6 are two distinct 

 teeth, segment 7 bearing four stronger teeth. 



Fig. 33. — Pericoma canescens, 

 Mg., a European species : 

 a, larva ; b, pupa (after 

 Miall). 



2^able of Specks. 



Wing with two rows of depressed scales on 



all the veins from the base to the middle, 



where they gradually develop into bristly 



hairs 



Wing without scales, except small ones in 



the nature of tufts forming spots at the 



tips of the veins or at or near their forkings. 

 Wingmembrane completely covered with com- 

 paratively soft black liairs, in addition to 



those on the veins cnmandalei, Bnm., 



Wing membrane wholly destitute of hairs 



(except an isolated one or two near the 



margin and a few at extreme base of wing) ; 



the liairs placed exclusively on the veins. . o. 



[x>. 287. 

 sqiiaiiunervis, Brun., 



[p. 237. 



