Mav 1, 1895. 



KNOWLEDGE 



113 



THE WINTER LIFE OF INSECTS-II. 



By E. A. BuTLEE, B.A., B.Sc. 



IN our last paper we considered the manner in wbicli 

 the Coleoptera. or beetles, spend the winter. Turning 

 now to the Hymenoptera, we find insects whose 

 economy is of a totally difl'erent type. In one 

 section of this order, that which includes the bees, 

 wasps and ants, we come across the social organization ; 

 with this comes in care for the young, associated with a 

 large amount of division of labour, effected by the existence 

 of workers in addition to males and females. This special 

 economy is accompanied by peculiar arrangements for the 

 continuation of the species through the winter. Amongst 

 British bees, tlie only species that are social in habits are 

 the hive-bee and the humble bees. The former we may 

 neglect, as provision is made by man for its maintenance 

 and well-being ; but the latter, as they have to depend 

 upon their own exertions alone, will yield us good illustra- 

 tions of nature's methods. The economy of the humble 

 bees is somewhat like that of the social wasps, and differs 

 considerably from that of ants. In both humble bees 

 and wasps, it is the females, or queens, large, stout-bodied 

 insects, that survive the winter, the miles and workers 

 perishing. They are impregnated in autumn, but do not 

 produce eggs till the following sprint. During winter they 

 retire to some sort of shelter and become torpid. Mr. 

 F. Smith speaks of finding humble bees, not in their old 

 nests, but " in the accumulation of rubbish under clumps of 

 furze, in the dry rotten wood of decaying trees, under moss 

 in woods, and repeatedly under stacks of turf on commons." 

 These were all found singly, not in clusters together. 



With wasps the case is rather different, as an experience 

 of Mr. T. E. Billups will show. He was entomologizing 

 in January, some years ago, on Wimbledon Common, when 

 he saw three queen wasps flying lazily about the remains 

 of a felled oak. On ripping off the bark in one place, he 

 found no less than thirty-eight more, all in a state of 

 torpidity, and huddled together as close as they could be 

 packed. But though torpid, they were not far gone in 

 their lethargy ; the warmth of the hand was suffi.;ieut to 

 restore thtm to activity. Ths wasps in this instance 

 were Ve.tpn t/ermanica, and they were accompanied in their 

 winter retreat by miny beetles of various kinds. Great 

 numbers of the same kind of wasp were once found 

 hybernating in a room used for storing furniture. The 

 goods were covered with blankets, and many of the wasps 

 were clinging to these; others had dug tneir mandibles 

 into the rough woodsvork of the room, thus supporting 

 themselves by their jaws, as if conscious thit their limbs 

 would become too benumbed during the cold weather to be 

 entirely trusted to. 



Upon such hybernating females as these depends 

 entirely the establishment of new colonies the next year, 

 the population of each nest being the offspring of the 

 queen who founded it. Hence it follows that, with the 

 exception of the hybernating females, the wasps and 

 humble bees of any given year are not the same individuals 

 as those of the year before, and the nests of one year are 

 not those of the preceding. In this fact we tiad the 

 explanation of the great variation in the numbers of wasps 

 that marks different seasons. One yeir they will swarm 

 to such an extent as to become an intolerable nuisance, 

 while, perhaps, the next year very few will be seen any- 

 where about. The numbers must largely depend upon 

 how many impregnated females manage to survive the 

 vicissitudes of winter, since the death of each single female 

 will mean the prevention of the birth of a whole nestful, 

 which may reach a total of some hundreds. And, as 



prevention is better than cure, it should be remembered 

 that prowling wasps seen in early spring are these very 

 queens, which are even then beginning to bestir themselves 

 about the foundation of their annual brood ; hence the 

 destruction ol one of these is equivalent to cutting off 

 a whole army in the summer-time. 



With ants the case is difl'erent. Here the workers 

 hybernate as well as the females, and therefore the nests 

 are more correctly to be described as perennial than annual. 

 The males appear, usually, to die in the autumn, shortly 

 after pairing ; but this is not universally the case, for Sir 

 John Lubbock records having kept some males of the red 

 ant [Mi/nnicn ru/finodis) from the month of August, when 

 they were hatched, till the following spring, one of them 

 even living on till the middle of May. However, the usual 

 occupants of the nest in winter would be workers and 

 females, and hence the ants of these sorts met with in one 

 season are in many cases the same individuals as those 

 that were to be seen the year before, though the males 

 would probably, as a rule, be different ones. Of course, in 

 addition to these, new members belonging to all the 

 divisions are hatched each year. It need hardly be 

 mentioned that ants, unlike bees and wasps, hybernate in 

 their own nests. 



Turning now to the order Lspidoptera, or butterflies and 

 moths, we find a still greater variety of habit. If there 

 is one creature that, more than another is mentally asso- 

 ciated with sunshine and summer skies, it is the " gilded 

 butterfly," and yet, warrantable as such association for the 

 most part is, this is the very order in which, if we take it 

 all round, we find the most numerous examples of activity 

 during the winter. It is true that a very large proportion 

 of the species belonging to this group are quiescent in 

 the winter in one or other of their stages, but yet, as if on 

 purpose to supply the proverbial exception to the rule, 

 there are some that actually choose the winter months as 

 the time of their emergence as perfect insects, and indeed 

 as their sole time of existence in that form. Thus we 

 have the November moth ( Oporahia dilutata), a thin- 

 winged, slight-bodied, grey insect, the colour of whose 

 wings is a good match to the cloudy skies that characterize 

 the month of its introduction to the world as a flying 

 creature ; the winter moth [Cheimatibia bnimata), a warmer 

 coloured, ihougU equally fragile little moth, whose brown 

 fore-wings, like the grey ones of its predecessor, are 

 crossed by a number of delicate wavy 

 lines ; the early moth (Hi/beniia ruin- 

 capraria), a larger, though equally fragile 

 insect, which derives its name from its 

 habit of appearing during the first two 

 months of the year; the spring usher 

 {llijberma leucopbearia), a very pretty 

 insect which appears a little later, but is 

 still only a harbinger of spring ; and 

 several others of the same type. It is a 

 noteworthy fact that the majority of these 

 winter moths have, so to speak, effected an aWa) ; natural"5izc. 

 economy in wing miterial, in th it their 

 femiles are either quite destitute of wings (Fig. 1), or 

 have them reduced to such ridiculously small dimensions 

 as to be quite useless for flight. The males, on the other 

 hind, have ample, though very weak, wings. The females 

 thus run little risk of becoming the sport of tempestuous 

 winter winds, and are enabled to cling to the twigs of the 

 food-plant and perform their maternal duties independently 

 of weather. 



The above insects all belong to the section called 

 geometric moths or loopers, in allusion to the curious 

 arched position taken by the caterpillars in walking, a 



Fig. 1.— Wing- 

 less Female ol 

 Mottled Umber 

 ( Ui/bernia defoli- 



