274 t'^'^y- 



double-brooded like its host. This I have found to be the case ; the 

 second brood, however, are much less plentiful and darker in colour, 

 T found a few at Oxford, and the only species that appeared with it, 

 that it was likely to infest, was the scarce Andrena angiistior, Kirb. 

 r. Smith and Shuckard both took it at Hampstead infesting Panurgus 

 ursmus, Gmel., one of the Apidce ; the latter in fact says that it is 

 restricted to this species. 



Sopworth Rectory, Chippenham : 

 January, 1887- 



VARIABLE MOULTING IN OEGYIA. 

 BY PROF. C. T. EILET, M.A., F.E.S. 



Dr. T. A. Chapman's remarks on the moulting of the larva of 

 Orgyia antiqua (March number) have just fallen under my notice. 

 It may interest him to know that in 18G8 I called attention to the 

 fact that the male larva of Orgyia leucostigma undergoes one moult 

 less than the female larva (First Report on the Insects of Missouri). 

 The variation from the normal number of moults (3 for ^ , 4 for $ ), 

 noticed by him in anfiqua, has also been noticed in leucostigma since 

 the publication of the report referred to. As to some of the questions 

 which Dr. Chapman raises, I would say that a pretty extensive ex- 

 perience in roaring larvae of all Orders leads me to the conclusion that 

 there is a very general tendency in individuals to vary from the normal 

 number of moults in the species ; that whenever there is much discre- 

 pancy in the size of the sexes, the smaller (usually the male) undergoes 

 a less number of moults (universal, I believe, in the Coccidce), and that 

 the variation in number of larval moults, except where, as in these 

 cases, it is sexual, and presumably predetermined in the egg, is de- 

 pendent on food-supply rather than hibernation. In frequent-moulting 

 species like Teneh'io and Dermestes, I have shown by experiment* that 

 there is a relation between scarcity of food (and consequent retarda- 

 tion in development) and increased number of moults, and think it 

 may be stated as a very general rule that moulting is correlated with 

 rate of growth and nutrition, those species which have a short larval 

 existence, generously nourished, exuviating least. A rule applying to 

 the class is presumably applicable to the individual. 



Newton, Kans., U. S. A. : 



March 2lst, 1887. 



* See Ann. Rep. U. S. Entomologist for 1885, and Am. Naturalist, about 1883. I write on a 

 Pullman, tn route for California, else would give specific references. 



