126 



KNOWLEDGE. 



[July 1, 1892. 



problem of the electric lighting of mines bas not yet been 

 tboroughly solved, but success seems to lie in tbe direction 

 of a portable glow lamp -worked by a secondary battery. 

 This may be made very light, and the extra cost, which at 

 the present moment is unavoidable, is more than saved 

 by the preservation of life and Umb and the altogether 

 more satisfactory condition of tbe miner. Swan has in- 

 vented an indicator which he attaches to his portable 

 lamp. This depends on the observed fact that a red-hot 

 platinum wire glows more brightly in an atmosphere 

 chai-ged with fire-damp than in pure air. 



For intensity of illumination glow lamps can never 

 compete with arc lamps, but the advantage of the foi'mer 

 lamp is that they may be distributed at wiD, and concen- 

 tration in one place, which is often a drawback, is 

 avoided. 



BEE PARASITES.-I. 



By E. A. Butler. 



THERE is no other order of insects that has made 

 such strides in the cultivation of architectural and 

 constructive talent as the Hymenoptera ; and con- 

 sequently, whenever the subject of insect skill is 

 under discussion, the majority of the illustrations 

 are sure to be taken from this order. Whether as exca- 

 vators, stone-masons, cai-penters, or workers in wax or in 

 paper, many members of the Hymenoptera have made 

 their mark in the world, and bees, ants, and wasps in 

 particular have attained a high degree of excellence in one 

 or other of these crafts. While the majority of insects are 

 to a great extent wanderers on the face of the earth, having 

 no definite spot with which their fortunes are inseparably 

 associated, dwelling nowhere in particular, but, like 

 nomads, living from hand to mouth, and prepared to take 

 up temporary quarters wherever they may chance to find 

 themselves at the end of a day's wanderings, most of the 

 above-named have what may be more or less correctly 

 called homes, fixed places of abode which they have care- 

 fully selected for the rearing of their families as well as for 

 their own private residence, places in which they may be 

 expected to be more or less continuously found, and upon 

 which they often expend a vast deal of labour to fit them 

 for the double pui-pose of a retreat for themselves and a 

 shelter for their brood. The sense of proprietorship is 

 thus developed, and its accompanying anxieties and 

 responsibilities have to be faced, even if, as is often the 

 case, only for the short period of a single summer season. 

 The establishment of a home, and the accumulation of 

 stores therein, creates a temptation to less thrifty beings 

 to profit by the industry and skill that have achieved these 

 results, and burglary and swindling thus become pro- 

 fessions amongst insects as well as amongst mankind. It 

 is in the existence of this, so to speak, landed proprietor- 

 ship amongst the Hymenoptera, this elaborate construction 

 of dwellings and ad%'ance in social babits, together with the 

 dangers and risks consequent thereupon, that is to be 

 found the reason for the numerous remarkable relations 

 into which so many of them are brought with other insects. 

 We have already seen good examples of this in the ants, 

 and we now propose to take other illustrations of a some- 

 what difierent character fi-om a kindred race. It is not 

 with the hive bee that we shall concern ourselves ; this 

 insect is so artificialized through its close alliance with 

 man, that it has no chance of furnishing such good 

 examples as those species exhibit which have only their 

 own cleverness and courage, unbacked by the assistance of 

 superior beings, to depend upon in endeavoiuing to main- 



tain their place in the world. Of these wild bees we have 

 many British species, some of which — the humble bees — 

 are social, while the rest are solitary. But both sections 

 are alike subject to the attacks of thievish depredators, 

 derived either from their own order, or from other groups, 

 and the reason for the parasitism therefore is to be found, 

 not so much in the development of the social instinct, as 

 might perhaps have been expected from the example of 

 the ants, as in the efi'ects produced by architectural skill 

 and forethought, the securing of a safe retreat and supplies 

 of food, which serve as prizes to tempt the cupidity and 

 appeal to the indolence of the unthrifty. 



Bees are subject to the attacks chiefly of other bees and 

 of flies, and the parasites in some cases closely resemble 

 their hosts, but in others are quite unlike them. We may 

 first consider the parasitism of the social bees. Apart 

 from the hive bees, all British social bees belong to one 

 genus, called Bombiis. The word was coined by the ancient 

 Greeks in imitation of tbe deep bass humming which these 

 bees produce during flight, whence also their English 

 names of humble or bumble bees. Some fifteen species of 

 these insects are now reckoned as inhabiting the British 

 Isles, and, like other social insects, they exist in three 

 forms — males, females, and workers. Great differences in 

 size appear in these. The females are by far the largest, 

 and are the well-known great, hea^■y, loud-humming 

 creatures that fly swiftly straight forward in a " bee line," 

 or hum in a deep self-satisfied bass, on a sunny spring day, 

 round the sallow bloom. The males are considerably 

 smaller, and are generally very difl'erently coloured from 

 their mates, being eitber more brilliant or more variegated. 

 The neuters are the smallest of all, and are usually more 

 or less like miniature reproductions of the females, several 

 sizes smaller. Their nests are not very numerous in 

 individuals, and each owes its foundation to the exertions 

 in early sprmg of a hibernated female, who is thus both the 

 foundress and the widowed mother of the colony, her 

 spouse having died the previous autumn. The first 

 members of tbe colony are workers, and the grubs which 

 produce them are fed with pollen and honey collected by 

 the great queen mother. When they arrive at maturity, 

 they imdertake the work of the nest, providing food for 

 the later members of the family. As the season advances, 

 males and females are produced, which are destined to 

 become the founders of next year's colonies, their mating 

 taking place in the autumn, though the progeny is not 

 produced till the next season. Such, in very brief outline, 

 is tbe life-history of a Bomhus. Now, there is a genus 

 called Psithynis or Apathux, superficially very much like 

 Bowlms, so much so in some species that a novice would be 

 sure to regard them as the same insect. These are the 

 parasites, and their economy is quite unlike that of the 

 Bombi. They enter the nests of the latter, deposit their 

 eggs there, and leave their ofl'spring to be cared for and 

 fed by the legitimate owners of the nest, while they them- 

 selves do nothing towards their maintenance. No labours, 

 therefore, either in the collection of food, or in tbe 

 construction or repair of nests, devolve upon them, and 

 there is thus no need for workers as distinct from males 

 and females, and hence we find that in this genus no such 

 things as workers are known, there being only tbe two 

 sexes as in solitary insects. 



Fm'ther, as pollen collecting, to provide food for the 

 young, is one of the chief occupations of the industrious 

 bees, these parasites, having no need to undertake this 

 labour, are unprovided with the necessary apparatus. 

 Tbe most important part of this apparatus consists of 

 what is called the " corbicula " (little basket) (Fig. 1). 

 The tibiEE of the hind legs of the female and worker 



