ENEMIES OF APHIDES 263 



Sepfe?nber ^th. — Length, i6/6oth of an inch, 



September ^th. — Length, 6/2oth of an inch The bulk of the 

 insect increases much faster than the legs, which are now relatively 

 much smaller, and, after feeding the larvae, are now sometimes so 

 distended and heavy as to be unable to crawl any distance of the 

 vertical sides of the glass cover, and they fall from the height of an 

 inch or two, rolling over on their backs. 



September ^th. — Length of larvae, i/srd of an inch. They 

 seem very sluggish and unable to move. 



September loth. — Larvae have all cast their skins, emerging 

 from the discarded covering by a longitudinal slit in the dorsal 

 surface of the thoracic segments (I shall figure this cast skin in a 

 later section). Length now, 5/1 2th of an inch. Colours much 

 brighter. The black colouring of the extremities of the limbs is 

 due to the cast skin in which it is still encased is evident, the 

 fresh skin of the larva being clear. 



September i^th. — Larvae, a bare 5/8th inch long. Now very 

 voracious, and of a flatter, broader shape than before. They now 

 eat thirty or forty Aphides apiece during the night, and appear 

 much distended. They make no attempt to ascend the glass, and 

 appear never to feed in the daytime, unless deprived of food at 

 night. When fully fed they are very thick, but in a few hours ^ 

 become flat, like a flat-fish in shape. 



September 22nd. — The larvae to-day became pupae, having 

 attained a length of over 5/8ths of an inch. The legs are now very 

 small in proportion to the body, which has become very broad. 



The pupae are enveloped in a dense ball of fine silk, nearly 

 spherical in form and attached to the under surfaces of the leaves. 

 The cocoon is less in diameter than the length of the larva, and 

 the pupa is completely hidden within, a contrast to some of the 

 Hemerobiidce, which are so slightly covered as to leave the pupa 

 visible. The respective pupae are shown on Plate XIII., at 

 Figs. 9, ga, and 10, 10a, where the difference in appearance is 

 well displayed. 



Some species of Hemerobiidce have a curious habit of covering 

 themselves partially with the skins of the exhausted Aphides, which, 

 by a peculiar jerking action of the head, they throw backwards, to 

 find a lodgment among the strong bristles of the back and sides. 



