214 THB entomologist's record. 



more freely under such humid conditions, makes it highly probable 

 that the variety, if the species really spreads to us from a colder region, 

 is the older form. The comparatively ill effects (so far as delay is 

 concerned) on its ally P. Jiavicincta, is not at all unexpected, as the 

 latter is a comi)aratively southern species, and hence in its more 

 northern habitats probably carries on a more precarious existence in 

 abnormally wet and cold seasons, than in more southern localities. 

 The baking of the ground in 18^4, mentioned by Mr. Webb, must have 

 been very partial. From June to September was one continuous down-pour 



in most districts — rain, nothing but rain." " Mr. Tutt writes again on 



April 3rd : — "I am much interested in the notes which attempt to explain 

 the bad season for lepidoptera of 1 8ii4. Since probably no two species have 

 identical habits, it is clear that no explanation relating to one species 

 will exactly suit another, and it is only when there is a general failure 

 that some general cause or causes can be attributed. But our discussion 

 has brought out the fact that it was rather a partial than a general 

 failure, and hence it is still more difficult to fix the peculiar conditions 

 which united to bring about the result. Mr. Bowles' experience sub- 

 stantiates to the hilt my statement re double broods, and the effect on 

 the resultant larva?. The young larvte which hatched from the eggs 

 of this second brood of S. fetralnnaria, could not possibly reach that 

 stage at which they hybernate = rest (i.e., the pupal stage), and hence, as 

 he shows, the whole mass of young larva? which he describes were, 

 with the exception of six, absolutely wasted. His sleeves, too, being 

 exposed to natural conditions, are sufficient proof of the absolute 

 destruction which took place in nature. Mr. Kobinson seems somehow 

 to have misunderstood my statement. His argument all round ju'oves 

 my contention. Certainly " liybernate as larva? " means " pass the 

 winter in the larval state," but not " simply " this. We use the term 

 " hybernation " and " aestivation " in a much more restricted sense, 

 viz., for the absolute resting periods of insects in summer and winter. 

 For this absolute resting period, natural selection has fitted some insects 

 at some particular point of their existence — egg, larva, pupa or imago. 

 They must reach this point or die. Mr. Bowles' S. tetrahinaria, instead 

 of spending their resting period as pupa?, emerged. The imagines did 

 not take on the resting period, but paired, laid eggs, and died. Tlie 

 eggs did not take on the I'esting period, but hatched. The young larva? 

 did not take on the resting period, but went on feeding to reach tlieir 

 proper resting period, and died in the attempt ; only six, Mr. Bowles 

 tells us, reached the pupal condition where the resting period was 

 natural. These I presume he treated artiMcially to obtain the result. 

 I saw Mr. Porritt's lai'va? (some dozens at least), of Calliinorpha 

 hcra, hybernating last Christmas, all absolutely in tlie same skin 

 (1 don't know which) ; natural selection has bred, in the course of 

 ages, the reaction of hybernation into these larva? at that age (i.e., 

 in that skin) ; if one of these larv* nibbled just enough during 

 the winter to cast that skin, Mr. Robinson would find that he 

 would have to feed it up or it would die ; that it nibbles but does not 

 cast that skin is nothing to the point. The resting period of C. hera 

 may include nibbling. But the nibbling must not be sufficient to make 

 the larva moult, for having moulted that skin and passed the hyber- 

 nating stage, it would be beyond Mr. Robinson's power to comjjel that 

 larva to hybernate in the next skin. I carried out some most interest- 



