NOTES ON COLKOPTERA. 35 



attack, as the best substitute, the living ones, but it will be invariably 

 noticed that the weaker the tree, the more liable it becomes to the 

 attacks of the Scoh/tidac. 



On the seasonal dimorphism of Melanitis leda. 



By C. A. BIRD. 



Looking through my Indian notes, I find some interesting particu- 

 lars relating to the two forms of the species of butterfly which, I 

 believe, until 1889, or thereabouts, went under the two names of 

 Melanitis leda and J/, isiiiene. 



On October 15th, 1889, I obtained a female of the form known as 

 M. leda. By next day I had obtained 80 eggs. These hatched out 

 in five or six days. The young larvfe fed up well on grass. Two 

 were accidentally injured, a few escaped and a few died. The 

 survivors began to suspend themselves on the 11th November, and 

 between the 12th and 16th November, 18 pupated. From these I 

 obtained 16 imagines. They began to emerge on the 20th or 21st of 

 November, when I was unfortunately absent from home on duty, so 

 that I found five out when I returned on the latter date. One of 

 these five was of the form leda, the rest, to my surprise, were of the 

 form ismene. All the remainder were of the form ismene. I feel sure 

 of this, although two of them escaped so suddenly that I only had a 

 glance at them as they flew away. I thought I had made a discovery, 

 but I afterwards read a notice in a number of Tlie Asian^^ of the same 

 year, but of an earlier date, showing that the fact of these being of 

 one and the same species was already known. 



I suppose this is an example of seasonal dimorphism, but the 

 following facts must be remembered. One specimen out of the 16 was 

 of the same form as its female parent, and, in nature, the two forms 

 overlap in the matter of periods of appearance. 1 took the form 

 leda in the months of August, September, October and November, and 

 the form ismene in October, November and December of the same 

 year ; so that both forms were on the wing in the months of October 

 and November. I find, from my diary, that the first specimen of is)nene 

 was taken in the third week of October, that is within a week after the 

 date on which the batch of eggs referred to above were laid. [We 

 have ourselves touched on this subject in our last Presidential address 

 to the City of London Entomological Society. There are some very 

 interesting facts relating to ••' wet " and " dry " seasonal forms in 

 Tlie Journal of the Asiatic Societi/ of Bemjal, vol. Iviii., by L>oherty, 

 and in the Butterjiies of Sumatra, by Niceville. — Ed.] . 



* A magazine published in India (Calcutta, I believe), on the lines of The Field. 



i^CIENTIFIC NOTES AND OBSERVATIONS. 



The cocoons of Acherontia atropos.— My nephew and I carefully 

 exhumed the pupae of A. atropos last autumn, and we tried to extract 

 the "cell" complete. In this we failed entirely. There was not the 

 slightest cohesion, and in only a few cases did we manage to secure 

 small pieces of the side to examine. This, of course, in sandy soil. 

 I presume that in heavier earth there would be a better chance ; but 

 I am certain there is no trace of silk, and very little of ijuin. The 



