September 1, 1892.] 



KNOWLEDGE. 



165 



Fig. 5.— Riiby-tailod Fly (Chrij- 

 six igiiUaJ. Parasitic en bees. 

 Magnified 2i diameters. 



and beauty never fail to elicit exclamations of delight and 

 admiration when seen for the first time. The general 

 type of coloration is much the same in the various species. 



consisting of a sparliliug me- 

 tallic green or blue head and 

 thorax, and a polished ruby- 

 red abdomen. To see them 

 at their best, one should 

 take up one's post on a hot 

 summer's day by the side of 

 a steep, bare, clayey bank, 

 perforated with insect bur- 

 rows ; a specimen will soon be 

 seen coming flashing tlu'ough 

 the sunshine and settling on 

 the bank, where it will either 

 rest displaying its beauty 

 like a sparkling gem of ruby and emerald, or else run 

 about over the surface, quivering its antenna', and every 

 now and then tapping the ground with them in apparent 

 excitement. 



The diifereut species of this family frequent the burrows 

 of various Hymenoptera, and amongst others those of 

 certain bees, and lay their eggs in the cells in order that 

 the larviP hatched from them may devour the grubs for 

 which the cells were made. By the bees they seem to be 

 regarded with hostile feelings, whence the mtroduction of 

 the egg becomes a hazardous proceeding. But they have 

 a novel method of defence, which sometimes stands them 

 in good stead. The last few segments of the abdomen, 

 which taper away to a point, are, in a state of rest, tele- 

 scoped up and withdrawn into the body, which thus 

 appears to be more or less bluntly rounded at the end. 

 When these segments are thus retracted the abdomen 

 beneath is concave, and its junction with the thorax 

 being a small one and extremely flexible, the whole 

 abdomen can be bent under and folded back on the 

 under side of the thorax, the insect thus becoming, 

 but for its wings, almost globular. In such a condi- 

 tion, its hard and shining convex dorsal covering is all 

 that is exposed, and enemies cannot make much more 

 impression upon this than a dog .can do on a hedgehog 

 similarly folded up. When, therefore, hard pressed, the 

 Clinjxis is apt to adopt the policy of passive resistance, to 

 fold itself up, and drop to the ground, lying motionless till 

 the danger is past. The brilliant colours seem as though 

 they might be protective in function, dazzling, and there- 

 fore warning off the foe ; and it is conceivable that some 

 insects or other enemies might be deterred in this way 

 from attacking such bright objects. But if this be the 

 case, the insect saves itself by inspiring a fear that is 

 almost entu'ely unfounded, for though the C'lii/sidiihe are 

 bold and daring adventurers, they are not able to do much 

 damage, having but a feeble sting, or rather no real 

 poisonous sting at all, but. only a sharp o\apositor which 

 can give a slight prick. Moreover, their brilliance does 

 not always secure them immunity from attack, as the 

 following incident will show. Lepelletier de Saint Fargeau 

 records that he once saw one of these insects, named 

 Uediji-hium n'l/iuiii, enter the burrow of a solitary bee, and 

 being apparently satisfied with the arrangements within, 

 it came out and, turning round, began as usual to enter 

 backwards, in order to bring its telescopic abdomen into 

 position for depositing eggs. Just at that moment, how- 

 ever, the bee returned laden with provisions, when ensued 

 a scene very difi'erent from that witnessed by Smitli in the 

 case of the cuckoo bee related last mouth ; on seeing the 

 intruder, the bee at once pounced upon it, when the 

 parasite fell back on its usual defence of doubling up into 



a ball, becoming thus invulnerable to the bee's sting. The 

 latter, however, was not to be defeated in this way, and 

 proceeded to bite off its enemy's wings, dropping the body 

 to the-grotmd. Thus victorious in the contest, it entered 

 its burrow and deposited its load, and then went off on 

 another expedition, no doubt reckoning that it had nothing 

 further to fear from its humiliated foe. But the latter 

 was quite equal to the occasion, and, as soon as the coast 

 was clear, unfolded itself, crawled back to the biuTOW, and 

 successfully accomphshed its task. 



There is also a large family of exceedingly minute 

 Hymenoptera, called the Clcilrididir, which are parasites, 

 and which are equally resplendent with the ruby-tailed 

 flies, and sometimes even more so ; they are mostly of a 

 brilliant metallic green, or golden green, and may often 

 be found in great numbers amongst long herbage of 

 various kinds ; but they are so minute that they would 

 not be noticed unless carefully looked for. By sweeping 

 amongst such herbage with a net, large numbers of 

 specimens may often be found. Several members of this 

 large family are parasitic upon bees, and, as they are so 

 small, one laee's cell frequently contains a great number of 

 their larvse ; in the cells of the Anthoplumi , referred to in 

 our last paper, two species have been found together, and 

 it seems probable that one of them is parasitic on the bee 

 larva, and the other upon it, a by no means unusual 

 arrangement in the family. The larvte that feed upon the 

 bee-grub are exceptional in being extermd instead of 

 internal parasites ; they cling to its body and suck out its 

 juices, till it is completely exhausted. 



Few more remarkable life-histories are to be found 

 throughout the whole range of the Insecta than those of 

 the beetles which constitute the family Mdoidir, and which, 

 in some stages of their career, are entirely dependent upon 

 bees for their support. So strange and unexpected, indeed, 

 are the details of their metamorphoses, that they were for 

 some years a great puzzle to naturalists, and the combined 

 efi'orts of several most careful investigators were needed to 

 clear up the mysteries. The commonest members of this 

 family found in Great Britain belong to the genus MAnii, 

 and are generally known as oil-beetles (Fig. 6), because 

 they have the power of exuding from 

 their bodies, when handled, a yellow, 

 acrid, oily liquid. They are heavy- 

 looking insects of a dull bluish- black 

 colour, and wingless, although the 

 elytra or wing-covers are developed as 

 two flexible oval pieces lying over the 

 base of the abdomen. The abdomen 

 of the female becomes enormously 

 distended by the development of 

 the eggs, which, though individually 

 minute, are extremely numerous, 

 as many as four thousand having 

 been estimated to be contained in 

 the ovaries at one time. This enormous 

 fecundity has relation to the life of 

 hazard the young larva lives in its earliest days, in 

 consequence of which no more than a very small percentage 

 of those hatched from the eggs in all probability reach 

 maturity. The eggs are laid m a cavity in the ground, 

 which the female MrhiH excavates for the purpose in early 

 spring. The larva? hatched from these are minute but 

 very active yellowish creatures, with six legs and two pairs 

 of hair-like appendages at the end of the abdomen (Fig. 

 7). As soon as hatched, they climb up the stems of flowers, 

 such as buttercups and dandelions, lying in wait in the 

 flowers for that chance which may help them on to the 

 next stage in their life. Now, as the perfect insects are 



Fig. 6.— Oil-Beetle 

 CMeloe proscara- 

 hretisj. 



