80 



rsrciiE. 



|Si-ptcnil>iT— O.lrilier iSS.i. ] 



pidit}-, undisturbed by warm and spring- 

 like weather at unseasonable times, 

 and this may accoimt for the vast in- 

 crease in numbers in species which 

 hibernate in the egg state ; it also 

 probably has a strengthening effect on 

 those which pass the winter as small 

 social larvae under a silken tent on the 

 ground, or which, like the Nocfitae, 

 hibernate in the larva state on the 

 ground or among dead leaves, and are 

 tempted 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 hiberna- 

 ting larvae and pupae, in two ways. One 

 is by encouraging the growth of mould, 

 which we know attacks them as soon 

 as, from excess of rain or humidity, 

 they become sickly ; the other by per- 

 mitting the continued activity of pre- 

 daceous creatures. These are very 

 numerous. Moles continue at work in 

 mild winters, instead of burying them- 

 selves deep in the ground ; and mice 

 are constantlv actixc. These small 

 mammalia destroy great numbers of 

 Lepidopterous pupae, and they abound 

 in this district, as also do birds during 

 the winter in an extraordinarv degree. 

 As soon as severe cold sets in to the 

 north and east, the birds come down 

 in swarms to the open fields and shel- 

 tered hillsides of this district, and it is 

 hardlv necessary to point them out as 

 most industrious and persevering de- 

 stroyers of larvae. Predaceous beetles 

 and earwigs are generally on the alert 

 all through very mild winters, and al- 

 though they probably do not eat much 



at that time. and. indeed, are not \ery 

 plentiful in Pembrokeshire, they must 

 destrov many larvae and pupae, having 

 little else to subsist ujjon. Hut I believe 

 that the mischief done by all these 

 added together does not equal that done 

 bv the Onisci. 



" During mild winters these crusta- 

 ceous vermin increase and multiply, 

 and feed, and grow witliout check, till 

 in so mild a climate the^■ become a per- 

 fect nuisance, pervading everything 

 indoors and out. It was hardl\' possible 

 to keep them even out of the breeding 

 cages, where thev would get introduced 

 when verv small and unnoticed — or 

 perhaps in the egg state — hunt out and 

 destroy every larva and pupa, and grow- 

 large and plump without ever siiowing 

 themselves above the leaves and rub- 

 bish. Doubtless, their industrv out of 

 doors was in the same proportion, and 

 my impression is that they approached 

 very near to completely exterminating 

 many species that would naturallv be 

 common here. Severe cold seems to 

 destrov some of them, for thev are not 

 nearlv so numerous now. and it cer- 

 tainly puts a complete stop to their 

 destructive operations during a time 

 when larvae are most especiallv helpless 

 and lial)le to attack. To this, witli other 

 causes alreadv mentioned. I am inclined 

 to attribute the extraordinarv increase 

 in numbers of so man\' species during 

 the last three seasons, divided liy severe 

 winters. The winter now past has 

 been mild. and. therefore, a furtiier pro- 

 gressive increase camiot reasonablv be 

 expected : but I hope that the mischief 

 done in one mild winter mav not be 



