180 



THE YOUNG NATUBA.LIST, 



the country bad seasons have been positively beneficial to it." He proves 

 this by showing that bad seasons have impoverished the farmers, who for 

 want of stock have neglected their pastures, and that the DevilVbit Scabious 

 has consequently become much more plentiful, and artemis larvae have found 

 abundant food. He tells us how its range had become extended, and that 

 the larvae last year were numerous in fields where they had not been seen 

 before. Then he goes on, " unfortunately it was very cold about the time 

 the imagines should have emerged, and their number was by no means 

 proportionate with the number of larvae seen. There were, however, I hope, 

 enough to ensure a good show this year if the weather be propitious." 



But cold weather at the time the imagines should appear is not the 

 only thing that insects suffer from. Open winters and mild weather in 

 February and March tempt hybernating larvae from their winter retreat, and 

 after they have begun to feed again they seem much less able to resist cold 

 than they were before. Take the present year as an illustration. On the 

 1st of January I saw mushrooms gathered in the open fields in this immediate 

 neighbourhood. On the 16th of May the same fields were covered with 

 snow. Could anything illustrate more forcibly the character of our seasons, 

 and if I am told that this was exceptional, I would reply that such a season 

 may destroy to an extent that many more favourable years will not 

 restore. Hybernating larva? appear to bear considerable cold with 

 impunity. I have dug up larvae that were frozen stiff, and that could be 

 snapped like a twig. I have thawed such larvae with the warmth of my 

 hand, allowed them to crawl off on to the snow, to be frozen stiff again in a 

 few minutes, and this 1 have repeated more than once with the same larva. 

 But larvae subjected to extreme cold after commencing to feed up have never 

 recovered in any experiment I have tried, though certainly some must do so. 



Again, sometimes we have a cold summer, with rarely a glimpse of sun, and 

 frequent chilly rains. In such a season butterflies are seldom seen on the 

 wing, and their chances of pairing and depositing their eggs are few. 

 Crepuscular and nocturnal species may be equally adversely affected by a mild 

 winter and cold spring, but a damp summer does not prevent them appearing 

 on the wing and performing those acts necessary to perpetuate their race. 

 Diurnal species become torpid on a dull day, and a continuance of dull days 

 is fatal to them. There is in the insect world a wonderful amount of recup- 

 erative power, and a few favourable seasons coming together, might restore a 

 species to its normal abundance. But we do not get several fine seasons in 

 succession, or very rarely, and that is why our species do not recover their 

 position, while our insular position prevents all those capable of but short 

 flights from reappearing when once lost. 



