1880.] 55 



ecdysis. The old skin splits in the usual way over the dorsum of the 

 thorax, and the new larva comes out yellow and translucent, but soon 

 re-acquiring the sooty black, which is its usual colour. The whole 

 process occupies about 15 or 20 minutes, but may be much longer, 

 especially till the tail is quite free. The mandibles are well seen in 

 the freshly moulted larva. They have five acute reddish teeth, of which 

 the lowermost but one is the largest, and is serrate-edged. The middle 

 one is next in size, and the lowermost of all minute. Before pupation 

 the larvae creep persistently under any cover they can find, and become 

 fastened slightly to the surface on which they are lying by their own 

 exudations. They then become quiescent, and gradually get contracted 

 and thickened. Just before pupation, however, the larva is somewhat 

 elongated in shape. There is loose infolded skin at the tail end 

 (owing, probably, to crowding forward of the pupa in the old skin). 

 A small longitudinal split occurs over the second thoracic segment, 

 through which the yellow colour of the pupa is very distinctly seen. 

 This split extends forwards, forking at the head, and backwards, and 

 in from 5 to 6 minutes the pupa is free to the tail. The anterior 

 portion of the alimentary canal may be seen withdrawn from the mouth 

 — a short tube with a black speck generally at the end of it. The 

 posterior portion of the gut, however, is not cast off so soon, and 5 or 

 6 minutes more elapse before the pupa is quite free of the old skin. 

 It is at first elongated and larva-like, but soon becomes broadened and 

 shortened. 



The time occupied by the whole batch in going through this 

 metamorphosis is again longer than it took to hatch out, as the 

 hatching itself extended over a considerably longer period than the 

 laying of the eggs. Something again depends upon the season, but 

 apart from this, the tendency of the whole brood to " scatter," as it 

 were, like shot from a gun, is very obvious. If the 40 or 50 larva* 

 could be reared safely to this stage, they would probably take con- 

 siderably over a day to pupate ; and as there is a general divergence 

 in the whole batch, there is a much greater straggling in a few indi- 

 viduals. 



The pupa, like the eggs, is yellow ; as, on the contrary, the body, 

 in the alternating larva and imago stages, is black. This state lasts 

 for about 7 days, and its duration varies less with time and tempera- 

 ture than that of any other condition through which the insect passes 

 — say from 6 days to 7J. 



I have not noticed exactly how long the individual imago takes in 

 its exclusion from the pupa-skin — about as long, I should say, as in 



