84 



KNOWLEDGE. 



[Apbil 1, 189S. 



with in summfr muft have Lad a representative Fome- 

 wLtre or otbtr in the preci ding winter ; 

 must, in fact, either have existed itstlf in 

 its prefect or in some other form, or have 

 been represented by its parent, or, in some 

 few cases, by even a more remote ancestor. 

 By constantly keeping this in mind, we 

 shall have a clearer conception of the 

 problem before us, ^and its complexity will 

 be more manifest if we remember that 

 most insects appear in four more or less 

 distinct conditions — as egg, larva, pupa, and 

 Examples of all these may be found during 

 well as at other seasons of the year, and 



Fio. 2. — KoFc 



Beetle ( Cetonia 



aurata). 



perfect insect, 

 the winter as 



though the habit of each particular species is, as a rule, 

 unifoim, it is by no means easy to say just what are the 

 ccndilicns that determine which of these forms shall be the 

 winter one, and even closely allied species sometimes differ 

 in this rfsprct. The nature of the food and the time of 

 year when it may be obtained, of course, largely influence 

 the result ; but this is not the only factor of importance, 

 and probably much depends also upon the type to which 

 the insect belongs. This being the case, it will be best to 

 confidtr the different orders one by one. 



First, then, as to the Coleoptera, or beetles. A very 

 large number of species hybernate in the perfect condition, 

 and consequently there are absolutely more beetles to be 

 had in December than in July ; for by the time the hottest 

 weather comes round the spring beetles have died off, and 

 the next generation are either not yet mature, or if mature, 

 are not sufficiently hardened to be worth searching for. 

 The general course of the life of such insects would, 

 therefore, be somewhat as follows : eggs laid in late 

 spring or early summer by hybernated females, larva 

 flourishing in summer, becoming a pupa in late summer 

 or early autumn, and changing to an imago in autumn, 

 to remain thus, chiefly in retirement, during the winter, 

 and return to activity the following spring. Hence the 

 autumn beetles of the one year and the spring beetles of 

 the next would be largely the same ix;dividuals. 



Beetles are not amongst those insects that adopt a 

 fasting policy when they beccme mature. Their mouth 

 organs are well developed, and the amount of food devoured 

 after they reach maturity is often very considerable. 

 Carnivorous species, such as the ground beetles {Cai-aLiis) 

 and their smaller relatives, are vigorously predaceous 

 when mature, and as they become full-grown for the most 

 part in autumn, very little time is left them to gratify 

 their slaughtering propensities before winter sets in. 

 Hence in the general dearth of active life during winter, 

 and the consequent failure of their food supply, hyber- 

 nation is their only resource, quite independently of the 

 direct physiological effect which the lower temperature of 

 winter has upcn them. The vast accumulations of fallen 

 leaves that lie about in all directions form excellent places 

 of shelter, especially the lower layers, which are closer and 

 damper than the rest. Here the beetles lie, perfectly still 

 and in a semi-torpid condition, with their legs drawn up 

 to their sides, and their antennas turned backwards and 

 lying along the thorax. Moss also supplies a safe and 

 comfortable retreat to great numbers of species, chiefly of 

 the smaller kinds. If quantities of loose moss are collected 

 from the ground or from tree-trunks in March or April, 

 and shaken over paper, remarkable evidence will be obtained 

 of the extraordinary numbers that use such a shelter ; and 

 if calculations be extended from the small area dealt with 

 to the larger ones of fields or hedgebanks, some notion 

 may be formed as to the profusion in which some 

 kinds of insects occur in winter, notwithstanding that 



they keep themselves so completely out of sight. Many 

 others retreat beneath large stones or loose rocks, and 

 the narrower the space the more attractive the retreat 

 seems to be ; the insect will very commonly cling to the 

 under surface of the stone instead of resting on the ground, 

 thus placing itself back downwards on the roof of its 

 retreat instead of remaining on the floor. By this arrange- 

 ment, no doubt, it is safer during wet weather, and while 

 enjoying the necessary amount of moisture with which the 

 atmosphere is sure to be impregnated in suchenclosed places, 

 it is more secure from the inconveniences of a swampy soil. 



While carnivorous species find a good reason for hyber- 

 nation in the failure of their food supply, whatever may 

 be the actual temperature of the winter, vegetable feeders 

 which depend upon fresh leaves find it even more necessary 

 to retreat into obscurity when the leaves fall, and they 

 have perforce to suspend operations till the new season 

 clothes the trees again with foHage. The moss on tree- 

 trurks and the hollow stems of dead plants are among the 

 objects that afford suitable shelter for such as these. It 

 is astonishing what enormous numbers of beetles of 

 various kinds sometimes crowd together into small com- 

 pass in hollow stems and crevices around the roots of 

 plants. Especially is this the case when the plants occur 

 at intervals, and no shelter can be found between them ; 

 they form common refuges in which the insects of the 

 neighbourhood gradually collect as winter advances, just 

 as in severe floods the inhabitants of the flooded district 

 gradually retreat to the higher grorrnds as the waters rise. 

 A very good instance of this is to be seen in the horned 

 poppy {Glaiicium lutcum), the large yellow flowers and 

 frosted It aves of which form one of the most conspicuous 

 objects on the shingly shores of our southern counties. 

 The plant has a large woody root, which, growing as it 

 does from amongst the shingle, is often very irregularly 

 shaped and presents numbers of hollows and crevices such 

 as suit the requirements of hybernating beetles. If these 

 plants be pulled up during the winter, and shaken over paper, 

 large numbers of beetles will drop out from the roots and 

 the interstices between the dead leaves at the base of the 

 stem just above the level of the beach. Many of the 

 insects that thus take refuge in the poppy roots are not 

 in any way connected with the plants in their economy, 

 and simply use them as convenient resting-places. Simi- 

 larly, old and strong dock roots, hollow thistle stems, reeds 

 and such like, harbour swarms of beetles, especially of those 

 species that in their larval condition prey upon the plants. 



Large isolated tufts of coarse grass form another 

 favourite retreat, many beetles congregating amongst tue 

 roots, so that to be sure of obtaining them it is necessary 

 to remove the tuft entire and shake it over paper. The 

 bottom of a haystack is a very favourite resort for beetles 

 in the winter. Many, again, may be found under the bark 

 of trees, but this is not so much through their having 

 sought such places for shelter as because they have been 

 born and bred there. Just in the same way, beetles occur 

 in the large fungi that are attached to tree-trunks. Many 

 of these, however, will be in the larval condition, and the 

 same may be said of those that burrow in the solid wood 

 of trees. Here they are removed from many of the dangers 

 to which insects that live in the open are exposed ; very 

 few parasites can reach therrr, they run no risk of being 

 devoured by carnivorous foes, and the temperature in 

 which they live is much more equable. Their life is often 

 considerably prolonged, several years being sometimes 

 required for the completion of their metamorphoses ; of 

 course, it follows from this that specimens might be found 

 in winter in different stages, if only one could drscover their 

 whereabouts m their timber fortresses. 



