116 THE KNTOMOLOGIST's RECORD. 



I think sufficient evidence has been brought forward to show that 

 the theory of mimicry, or rather of common warning (synaposematic) 

 colours, which will always be associated with the name of Fritz 

 Miiller, may claim abundant examples in Africa as well as in the other 

 parts of the world in which it has already been proved to hold. 



Some notes on the pupal moult of Lepidoptera. 



By T. A. CHAPMAN, M.D.. F.Z.S., F.E.S. 



It occurred to me last summer to endeavour, if possible, to learn 

 something more of a curious action in connection with the spiracles 

 in the pupal moult of ('hara.rcs jasius {ante, vol. ix., p. 220). This 

 was a remarkable action like a continuous winking, performed by the 

 spiracular valves. 



The difficulty in this observation is in being present just when the 

 moulting takes place, and a considerable number of examples seems to 

 be the best means of getting over the difficulty, so that if one misses 

 one, one manages just to hit oft" another. There is also this advantage, 

 in having a large number, that one learns what hour of the day is most 

 likely to present an example. I tried several species, and succeeded 

 in making observations on Spliin.v ligustri, Snicrinthus ocdlatvs and 

 S. populi, Flialcra hiicephala, and Scolioptenjx lihatrir. In the case of 

 P. bncephala, moulting Avas much the most frequent from about 8 to 

 10 a.m., but in all the species it appeared to occur at all hours. 



In addition to the spiracular phenomena, I met with one or two 

 other facts that may bo worth reference. One of the most curious of 

 these was the colouring of the larval skin of S. Ubatri.v, over the wing 

 areas, preceding the moult. This has been well described, and figured 

 by Professor Poulton (Trans. Ent. Soc. Land., 1887, p. 302). As soon as 

 the larva begins to spin its cocoon, the cuticle over the fore-wing begins 

 to darken, and th^n that over the hind-wing, until, before the moult 

 takes place, the position of the wings is marked by two quite black 

 patches, very conspicuous on the green larva. The colour is entirely 

 in the superficial layer of the larval skin, and is moulted with it. The 

 questions as to how and why these curious patches of pigment arise 

 puzzled me very much, and I have not been able to formulate any 

 theory about them that I can advance with any confidence. The 

 colour of the pupa of S. libatri.r is a sooty-black, and it pupates in a 

 cocoon of leaves on a spray of the willow tree, on which it feeds. Is 

 the blackness of any use to the pupa? I can hardly think it is ; but if 

 it is, it must be by its absorbing all radiant heat that reaches the pupa, 

 and so forcing forward its development. This Avould, no doubt, be an 

 advantage to the insect in two ways. It would diminish the period 

 during which the insect occupied so exposed and therefore dangerous 

 a habitat, and, in the cold and exposed positions often occupied by its 

 food-plant, it might be useful in enabling the moth to emerge safely, 

 and find a hibernaculum before the season became too far advanced. 

 This is all clear enough, my difficulty is to believe that any very im- 

 portant amount of radiant heat would reach it through the leaves 

 with which it is surrounded. If a black colour is useful to the pupa, 

 it would, no doubt, l)e useful to the larva, l)ut then would it be of much 

 use only over so small an area, and do the wings require special forcing ? 



