242 



HARDWICKE'S SCIENCE-GOSSIP. 



The subject of this paper, is, however, one which 

 opens up a wide field for observation, and in which 

 much valuable information might be obtained even 

 by those who have not sufficient leisure to form a 

 local collection. 



Many of the species mentioned below are among 

 our commonest insects, while other not rare flies 

 may prove on observation to be cases of mimicry. 



One of the first things that a beginner at "fly 

 catching " would notice is the extraordinary similarity 

 between some of these insects and the bees and 

 wasps. In showing my Diptera to friends, I 

 notice that they constantly remark, "That is a bee, 

 surely ? " or " That is a wasp ? " And the editors of 

 " Little Folks " fell into the same error some years 

 since, for I have before me a volume in which, among 

 other instructive paragraphs for the young, I find 

 one on "Busy Bees," accompanied by a very fair 

 woodcut of several flies including Stratiomys, Tabanus, 

 and even Tipula, but without a single bee or wasp 

 among them. 



That the Romans and other ancients evidently 

 made a very similar mistake, owing to this resem- 

 blance, we shall see presently. 



Beginning with the Stratiomyidae, we find among 

 the species of Stratiomys a considerable similarity to 

 bees, especially when flying. 



My specimen of S. f areata was captured under the 

 impression that it was probably a bee, especially as 

 the insect, when settling on a plant, folded its wings 

 over the back in the same manner as do the bees. 



Asilus crdbroniformis (Science-Gossip, 1876, 

 p. 156, Fig. 85) is so called from its having rather 

 the habit of a hornet when on the wing, but when 

 captured, it is seen to be so entirely unlike a hornet 

 that, without further evidence on the subject, I can 

 scarcely believe it to be a case of mimicry. Much 

 more is Laphria ephippium, another fnsect of this 

 family, like a bee. This fly occurs in many places 

 on the Continent. 



In the Leptidse, I observed a remarkable case of 

 undoubted mimicry, the mimicked insect being in 

 this case, not a Hymenopteron, but a Neuropteron. 

 I was walking along a lane in Warwickshire one 

 June, some two or three years back ; the scorpion 

 fly {Panorpa communis), a neuropterous insect, 

 familiar to all who live in the country, was ex- 

 tremely abundant, the hedges swarming with them, 

 and after netting one or two of these, I thought I 

 had captured another, but on examining it, I found 

 it had two wings instead of four, and was easily 

 recognised as Leptis scolopacea. I have placed the 

 two insects in my collection side by side, and even 

 when compared closely they possess considerable 

 similarity with the wings folded. 



In both, the wings are mottled with brown spots, 

 the legs are longish and rather thin, and the abdomen 

 is also slender. 

 But when settling on a hawthorn bush, the insects 



were only with difficulty to be distinguished from one 

 another, so that it is beyond doubt that, the scorpion 

 fly, of which the body is rather hard, not being a very 

 palatable meal for birds, the Leptis takes advantage 

 of its similarity with this insect to escape being eaten, 

 it being a softer bodied insect and therefore better 

 food for birds. The fact that the Panorpa was by 

 far the more abundant insect of the two is in corro- 

 boration of this. 



The species of Bombylius, although called humble- 

 bee flies by some entomologists, do not much resemble 

 any of our British species of Bombus. They feed on 

 the juice of flowers, as does the humming-bird 

 moth. 



Though rather like some Apidse, my observations 

 would lead me to give my opinion against their being 

 cases of mimicry, but perhaps that may be because I 

 have not found the mimicked insect. As they dart 

 about quickly, they may not need protection. 



But it is among the flies of the family Syrphidaa 

 that we find the most singular resemblance with 

 Hymenoptera. Who has not seen the ubiquitous 

 drone fly {Eristalis tenax) buzzing on the window 

 pane, or, in late autumn, crawling wearily along the 

 sill, and who has not mistaken it for a bee (Apis 

 iiicllijica) 1 I have but to go into the garden and. 

 watch a patch of flowers ; there, beside the numerous 

 bees which come to gather honey, I am sure to find 

 some of these flies. And I have to look twice before 

 pronouncing them to be flies. If I take one of them 

 in my fingers, some non-entomological friend will 

 certainly exclaim, " Take care it does not sting 

 you ! " 



Baron C. R. Osten Sacken has pointed out that 

 the belief, universal among the ancients, that bees 

 originated from carcases of dead animals (oxen, &c), 

 undoubtedly owes its origin to this resemblance. 

 That belief is often mentioned in their writings (for 

 instance it is alluded to at great length in Virgil's 

 " Georgics," book iv. verses 285 et seq.), and has been 

 reproduced by the earlier modern writers, such as 

 Aldrovandi (" De Anim. Insectis," p. 58, edit. 1602), 

 and Moufet (Theatr. Insect., p. 12). 



The rat-tailed larvae of Eristalis thrive in putrefying 

 animal matter, and the very natural explanation of 

 the superstition is that the perfect insects were 

 mistaken for bees. 



Eristalis ceneus, as well as Chcilosia chrysocomus 

 closely resemble some of the Andrenidae, both in 

 colouring and in general appearance. 



E.floreiis, on the other hand, takes after the wasps 

 in its colouring ; some specimens of this fly would be 

 mistaken for wasps by any but an entomologist. 



In that respect it is not singular, for several 

 Syrphidaa are somewhat wasp-like when flying, but 

 perhaps the best imitation of a wasp is that afforded 

 by Chrysotoxicm arcnatum and C. octomaadatum: The 

 latter species is rare in England, but at Heidelberg 

 some few summers past, when wasps ( Vespa vulgaris) 



