506 Mr. C. L. Witliycombe's Notes on 



various forms occur. The trumpet-sliaped empodium is 

 probably a primitive, ratlier than a highly specialised organ, 

 since it occurs only in the first instar of the Hemerobiidae 

 and also in the archaic Psychopsidae (12). 



The abdomen is of ten segments, if we include the anal 

 papilla as a segment. This latter, bears two more or less 

 evaginable appendages, covered with hairs and best 

 developed in Osmylus. It is used as an additional leg, and 

 also occasionally as a brush to clean the body immediately 

 on hatching. When a moult is about to take place, the 

 larva attaches itself by this papilla, at the same time 

 secreting a yellowish sticky fluid, undoubtedly excretory 

 and from the Malpighian tubes. The abdomen is without 

 appendages except in Sisyra, which has ventral tracheal 

 gills. The first eight abdominal segments are provided 

 with spiracles, the only other spiracles being a pair on the 

 prothorax. Chaetotaxy is very similar throughout the 

 order, and, I think, important, but it can hardly be dealt 

 with here. 



After two moults, in each of which the skin splits along 

 the thorax and posterior part of the head, the larva becomes 

 full fed and spins a cocoon of whitish silk, using the anus as 

 a spinneret. The cocoon is generally rem.arkably small as 

 compared with the size of the larva and of the emerging 

 adult. There is often a tendency to double structure. 



The pupa is a pupa libera, but the appendages are not 

 movable until just before emergence. The pupa exhibits 

 all the characters of the adult, but the appendages and 

 abdomen are shorter, especially is this true of the wings. 

 The head is furnished with strongly chitinised pupal m.an- 

 dibles, with which a hole is cut in the cocoon at the end of 

 pupal life. The antennae lie over the wing rudiments at the 

 sides, the legs ventrally. Spines are often present on the 

 back of some of the segments, which aid in escape from the 

 cocoon. 



In due course the pupa bites a hole in the cocoon, and 

 generally crawls out of it completely on to a suitable 

 support. Here the pupal skin splits along the dorsum of 

 the thorax, the imago withdra\vs itself and may walk an 

 inch or so before the wings commence to expand. Wing 

 extension occurs basally at first, the tips of the wings 

 extending last of all. The whole process is very rapid. 

 Before taking to flight, a black or dark brown pellet of larval 

 excrement is deposited. This is hard and shining, enclosed 



