20 tJ"n«. 
Food of Boa/rmia rhomhoidaria. — I wish to substantiate what Mr. Horton says 
about the food of this insect. Here it occurs in abundance, the larvae always feeding 
on ivy. I have reared numbers on this plant, and never found them take other 
food. — E. Hallett Todd, Windrush, Eastern extremity of the Cotswolds. 
Notes on Variation. — Thanks to Messrs. Davis and Ingall for their communica- 
tions in Nos. 21 and 23 of the " Magazine" respectively. I agree with the latter in 
preferring constant varieties to a chance aberration from the type. 
On referring to my Notes in No. 11 of the " Magazine" — a year ago — I find I 
omitted one species, Tephrosia crepuscularia o( StSiinton (biu7idularia,J)hd.), which, in 
this locality is subject to a very fine and tolerably constant variation. This consists 
not in size, but in colour which is an uniform smoky dark grey, in which the 
indented whitish sub-terminal line is conspicuous. 
The species is common here, and I have taken the variety regularly, but in 
limited numbers, for some years past ; and this year I am glad to say I have a few 
ova from a dark female. 
As Stainton, in his Manual, gives Manchester as one of this species' favourite 
haunts, and as that district is well worked, perhaps some of your readers would kindly 
inform us if the variety I have described occurs there also. 
The numbers in which I have observed the variety may be stated roundly 
at 1 in 25 or 30 of the usual colouring. —John T. D. Llewelyn, Ynisygerwn, 
Neath, April 11th, 1866. 
Notes on " douhle-brooded" insects. — Warmth, when coupled with an abundant 
supply of good and nourishing food, has clearly so much to do with rapidity of 
development, that almost any insect may be forced by artificial circumstances into 
having a second brood during the same season , thus, I lately had Orgyia gonostigma 
producing two, and Clostera anachoreta producing three broods in one year. Without 
doubt a hot summer may and often does perform the experiment naturally for us, 
and for the same reason (like the "Mferi rosaria Pcssti") an insect is often double- 
brooded in a hot cUmate, when in a colder region there is only one brood in the 
year. Polyommatus Argiolus certainly appears twice a year in the south of England, 
but seems only to appear once in the north. There seems another and more obscure 
cause of a second brood, where there is in some individuals a very brief duration in 
the pupa state, this stage of development seeming almost, as it were, hurried on 
unnaturally. This never happens to a whole brood, but only to single individuals, 
and there is some evidence that the reproductive organs are often in these cases 
not fully perfected. Insufficiency of food seems also to retai-d development to a 
certain degree, but its natural effect is probably rather to lessen the size of the 
specimen — bred specimens of some insects especially are always small, and un- 
usually diminutive examines are sure to be recorded in dry summers. I do not 
mean to infer that these are the only causes of these effects, but that they are 
amongst the chief causes I have no doubt. Another curious fact connected with 
this twofold appearance of some insects is the difference between the size and 
colouring of the two broods, the most familiar example being that of the common 
turnip white butterfly, Fontia rapes, but the most striking being that of some species 
of CynipideB, the history of which cannot, however, be said to be as yet completely 
