INFLUENCE OF TEMPERATURE ON /' 51 



sickly; the other bj permitting the continued activil 

 predaceous creal u 



" These are verj numerous. Moles continue at work in 

 mild winters, iii.-dad of burying themselves in the 



ground ; and mice are constantly active. These small 

 mammalia destroy greal numbers of Lepidopterous pupae, 

 and they abound in this district, as also do birds during 

 the winter in an extraordinary degree. As soon as severe 

 oold Bets in to the uorth and cast, the birds come down in 

 swarms to the open fields and sheltered hillsides of this 

 id. and it is hardly necessary to poinl them out as 

 most industrious and persevering destroyers of larva-. 

 Predaceous beetles and earwigs arc generally on the alert 

 all through very mild winters: and although they probably 

 do n<>t cat much at that time. and. indeed, are not very 



plentiful in Pembrokeshire, they musl destroy many larva? 

 and pupae, having little else to subsist upon. I'm 1 believe 

 that the mischief done by all these added together d 

 equal t ha1 done by the < >nisci." * 



In his work on bark-beetles Eichhoff tell- as that the 



el ief faotors in t he growl h of these insect- arc g I weather 



and sufficient t I. An uninterrupted dry, and hence hot, 



summer checks the growth of 'he larvae, ami retards their 

 speedy development, and more often prevents a repetition 

 of the broods than an uninterrupted wet ami cold spring 



and summer. Hence on account of the great heat ami 

 drought mam trees survive which otherwise would he in- 

 hired by the later broods of bark-beetles. The most favor- 

 able conditions for the increase of bark-beetles arc doubtless 

 a warm early spring, a warm summer with frequenl rains, 

 and a Ion-' mild autumn. 



It is well understood in central Europe t ; ' num- 



bers of may-beetles die during a cold we\ May. After an 

 exceptionally warm and dry summer and autumn am- may 



Paycfo, iv. 83; abstract from Knt. Month. Mag., Jan. L882, 1. 



