﻿THE REARING OF LARV^. 187 



results. This bringing in early applies equally well to some 

 larvcie which hybernate full-fed, such as ISIacrothylacia rubi. I 

 have certainly done best with that species when I have brought 

 the larvfe into the warm in January. The reason why larvae do 

 better under this treatment may be that during the last few 

 weeks of hybernation, under normal conditions, the warmer 

 days wake the larvae up, but before they get sufficiently wide- 

 awake to feed properly, the cold night comes and makes them 

 dormant again ; this constant waking up without adequate feed- 

 ing weakens them to such an extent that, when they do come 

 properly out of hybernation, the usual drawbacks of rearing in 

 confinement finish off all but the most robust. By bringing the 

 larvae in early and feeding in a steady warm (not hot) tempera- 

 ture, this weakening period is cut out and the larvae are strong 

 and healthy. 



How soon it is desirable to bring the larvae in (they should 

 of course have at least two or three months of winter weather 

 out of doors) depends largely on the food-plant. I have brought 

 Coremia quadrifasciaria in as early as late January, but their 

 food can be obtained at any time. To bring in larvae only a 

 week before they would thoroughly awake out of doors is an 

 advantage, and this can often be easily managed even with larvae 

 which feed on trees or bushes. Suppose white thorn is the 

 food-plant ; then directly the buds swell and begin to show 

 green, a small branch or two can be cut and placed in a vase 

 of water in the warm. In a few days the foliage will be 

 right out— perhaps ten days or a fortnight before it is out in 

 nature. Some other deciduous trees and shrubs are amenable 

 to the same treatment, and the breeder is thus enabled to bring 

 in larvae which feed on them ten days or more before they would 

 out of doors be able to start feeding in earnest. 



Treatment of Pup^. 

 I have seen it stated in quite a number of works on the 

 British Lepidoptera that the pupae of burying larvae should not 

 be dug up, and that cocoons should not be interfered with. In 

 the great majority of cases I would unhesitatingly advise the 

 very opposite. In confinement many spinning larvae will make 

 their cocoons one on top of the other in such a way that if left 

 in position the imagines could never get out of those at the 

 bottom, while with those that bury I have already pointed out 

 how one end or corner of the pupating box will be patronised by 

 the majority of the larvae. Then, again, despite the greatest 

 care, insect pests may get established in the pupating material; 

 and if the pupae are left in it for months they may all be de- 

 stroyed long before the perfect insects are ready to emerge. 

 Another point about taking out the pupae is that they are then 

 much easier to handle and look after and to place, so that they 



