60 ENTOMOLOGY, 



caused the pupa-cases or flaxseed to dry up, and even 

 destroyed the parasites.* 



The canker-worm, tent caterpillar, and most larva? abound 

 less after wet and cool springs. The spring of 1885 was 

 unusually cold, rainy, and backward, and we noticed that as 

 the result the lack of caterpillars and other forest-insects, 

 as compared with the season of 1884, was very marked; 

 late in the summer and early in autumn there was a re- 

 markable scarcity of caterpillars on oaks, maples, poplars, 

 etc., while they were very abundant during the previous 

 autumn. 



An English entomologist, 0. G. Barrett, in an excellent 

 article on the influence of adverse or favorable climatic 

 changes on insect-life, states that in the south of England, 

 after an unusually cold winter, with no thaws, moths be- 

 came unusually abundant for several following seasons. As 

 he remarks: ' I think there can be no doubt that in the 

 case of those insects whose mode of life includes the 

 capacity for hibernation, their constitution is greatly 

 strengthened, and their chance of arriving at maturity in- 

 creased, if the cold of winter is sufficiently severe to induce 

 complete torpidity, undisturbed by warm and spring-like 

 weather at unseasonable times, and this may account for 

 the vast increase in numbers in species which hibernate 

 in the egg state; it also probably has a strengthening effect 

 on those which pass the winter as small social larva? under 

 a silken tent on the ground, or which, like Noctuae, hiber- 

 nate in the larval state on the ground or among dead leaves, 

 and are tempted out to feed by every warm and genial 



evening. 



" On the other hand, there can be no doubt that mild 

 winters act directly to cause the destruction of both hiber- 

 nating larvae and pupae, in two ways. One is by encourag- 

 ing the growth of mould, which we know attacks them as 

 soon as, from excess of rain or humidity, they become 



*C. V. Riley, Amer. Nat., Nov. 1881, 916. 



