﻿THE REARING OF LARViE. 113 



as regards the habits of Lepidoptera in their early stages and 

 the effect of various influences on the perfect insect, I do not 

 suggest that all I have to say is absolutely new, and a great 

 deal of it seems to me very obvious. But whether the points 

 are old and obvious or new and obscure, I trust their record may 

 possibly be useful in some quarters. I would, however, mention 

 that I do not write from the point of view of one who makes 

 a business of breeding Lepidoptera, but from that of the ordinary 

 collector, who may or may not have even a garden, and is cer- 

 tainly unable to give his larvae the natural surroundings and 

 conditions which the professional can do with his enclosed bits 

 of land, large garden-frame-like houses in which the food-plants 

 are growing, covered trees and shrubs, &c. 



Pre-hatching Influence on Strength of Larv^. 

 Every now and then the most careful of breeders comes across 

 a batch of larvae which fails unaccountably. I am convinced 

 that this is not always due to incorrect treatment. Many of our 

 Lepidoptera lay their ova more or less in batches. Now while 

 larvae hatched from the earlier laid batches will flourish, those 

 from the last batch, though treated identically the same, are 

 often most difficult to rear. This suggests that fertilization 

 weakens towards the end of laying. There is no doubt, too, that 

 many moths need pairing more than once adequately to fertilize 

 all the ova, as for instance, Palimpsestis octogesima. When I 

 first bred this species I found an extraordinary number of the ova 

 infertile, while of the hatched larvae a very small proportion 

 appeared strong enough to thrive. By subsequent experiment 

 I found that the octogesima female would readily pair up a second 

 or even a third time, and that the ova first laid produced strong 

 and healthy larvae. This may, perhaps, be one of the reasons 

 why octogesima is not more abundant, for the perfect insect is 

 comparatively inconspicuous, the food-plant is common, and the 

 larvae generally well hidden — points which should help the 

 species to increase and multiply. 



Fresh Air. 

 That plenty of fresh air is required by many larvae is un- 

 doubtedly true, but that is not due so much to the fact that each 

 individual larva wants a lot of air, as to the fact that in confine- 

 ment so many are frequently kept in a comparatively small 

 space that an abundance of fresh air is needed to counteract the 

 troubles that the overcrowding would otherwise cause. This is 

 demonstrated by the ease with which one or two quite large 

 larvae can often be successfully reared in a tightly-fitting glass- 

 topped metal box. It is obvious, therefore, that when larvae are 

 small in size or few in number, or both, fresh air is a minor 

 consideration, and nothing like so important, in most cases, as 



BNTOM. — MAY, 1915. L 



