Q [June, 



SO ; the nests o£ Bombyx neustria were to be found in scores on hawthorn 

 and blackthorn bushes ; B. ruhi and quercus became plentiful, and 

 Odonestis fotatoria so abundant, that the larvae could easily be col- 

 lected in hundreds, where hardly one could be seen before, and even 

 the empty cocoons were conspicuously numerous on the hedge-banks 

 in the winter. Emmelesia ajfinitata became a common insect, and 

 many other Geometrce turned up which had hardly been seen before. 



But in Noctuce the improvement was the most remarkable, as in 

 that group the scarcity had been most marked. 



Ajylecta herhida and Sadena thaJassina appeared close to the town ; 

 Xylophasia hepatica and Apamea gemina (both richly variable), 3fiana 

 fasciuncula, Orammesia trilinea, Noctua c-nigrum and festiva, Aplecta 

 nebulosa, Hadena dentina, and Olcga spadicea, all became abundant ; 

 Thyatira derasa and hatis, Acronycta Ugustri and megacephala, Leucania 

 comma, Itiisina feiiehrosa, and Noctua trianguhim, turned up more or 

 less freely ; Triphcena jantliina came commonly into the gardens, and 

 Leucania littoraJis on the sand hills, and Seliodes arhuii in the 

 meadows, both increased greatly in numbers. These, to be sure, are 

 not remarkable species to obtain, the wonder was that they should have 

 been previously rare or apparently absent. Other and scarcer species 

 were also secured, but I am now referring to captures in home lo- 

 calities, which had been worked from year to year. Another species 

 which wonderfully increased in numbers was Pyrausta ostrinalis, 

 which actually swarmed last year. 



Here we seem to have a direct example of cause and effect, but I 

 am not prepared to say that the effect always arises in the same way. 

 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, like Bomhyx neustria, hibernate in the egg state ; it also pro- 

 bably has a strengthening effect on those which, like the species of 

 Arqynnis already mentioned, pass the winter as small social larvae 

 under a silken tent on the ground, or which, like the Noctuce, hibernate 

 in the larva state on the ground or among dead leaves, and are teuipted 

 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 hibernating larvae and pupae, 

 in two ways. One is by encouraging the growth of mould, which we 



