1SS2.I 3 



For instance, from the second brood of Colias Edusa whicli was 

 so abundant in 1877, eggs were obtained, and tlie larvae fed up and 

 turned to pupae, but, as far as I can ascertain, none emerged. My old 

 friend, Mr. Birchall, wrote me that all his pupse shoived the yellow 

 colour of the ivings in December and then died. This colour of the 

 wings, as we all know, only shows itself when the insect is nearly ready 

 to emerge, and these Ediisa pupae following inherited habit tried to 

 emerge in the winter, so as to hibernate, as they are well known to do 

 in the perfect state, but from insufficient warmth and sunshine were 

 unable to muster sufficient strength. 



Again, in 1880, there was a wonderful immigration of Vanessa 

 cardui, the usual numbers in this district, as in others, being enor- 

 mously re-inforced by — evidently- — a portion of the vast army that 

 migrated across Europe. Very late that autumn the Eev. Clennell 

 Wilkinson, of Castlemartin, Pembroke, found, to his great surprise, 

 that larvae of V. cardui were tolerably common on the thistles on the 

 warrens near his residence. All the tall thistles were dead, and these 

 larvae were feeding, at the beginning of October, on the young plants 

 close to the ground, making their nests among the radical leaves. 

 Some of these larvae he took home, and, by great care, two of them 

 entered the pupa-state, October 17th and 20th, and one emerged (in- 

 doors) November 20th of the same year, 1879. The rest died. This 

 failure of instinct on the part of the immigrants surely explains, in 

 some degree, the fact that last year the insect was more than usually 

 scarce, hardly any appearing to have hibernated, and also why an in- 

 sect with such a power of increase in a suitable climate is so uncertain 

 and variable in its appearances in one that is unfavourable. 



With reference to the second class of cases — those in which a 

 species always present is periodically common or scarce— much has 

 been written, excessive rain being usually assigned as the cause of 

 diminution in numbers, sunshine as the cause of increase. Without 

 doubt these causes act to a very large extent, large numbers of larvae 

 being actually drowned by continued heavy rain, and others rendered 

 liable to disease, but a little evidence has come under my notice, 

 pointing so distinctly to another influence of equal potency, that I 

 think it well worth recording in detail. 



It may be within the memory of some readers that at the end of 

 the first season that I was here at Pembroke (1875), I contributed to 

 this Magazine some notes on Pembrokeshire insects, in which I re- 

 lieved my soul by a vigorous grumble at the (entomological) barren- 

 ness of the land. It appeared that although in the preceding winter 



