HARDWICKE'S SCIENCE-GOSSIP. 



243 



were very troublesome, there was rather an abundance 

 of C. octomaculatum. The yellow and black markings 

 on the abdomen, the wings with a brownish tinge, 

 especially along the anterior margin, and even the 

 long antenna?, all combine to produce an appearance 

 very like a wasp. Owing to this fly being about 

 when wasps are plentiful, it doubtless obtains some 

 protection from this similarity. 



Still more closely does Vohicclla bombylans mimic 

 several species of humble-bee (Bombus), moreover it 

 is subject to considerable variety, and each of the 

 different forms exactly reproduces the colouring of a 

 corresponding type of Bombus. 



In Britain we have two varieties, distinguished by 

 many entomologists as different species, V. bombylans 

 and V. plumata. 



Now in the former the thorax and abdomen are 

 black, the thorax is covered with black hairs, while 

 the tip of the abdomen is clad with hairs of an 

 orange-brown colour. This is precisely the colouring 

 of Bombus lapidarius and B. rupesiris. In the 

 latter, most of the thorax is clothed with yellowish 

 hairs. There are patches of yellow on the sides of 

 the abdomen near its base, while its tip is covered 

 with whitish hairs — an arrangement of colour almost 

 identically the same as in Bombus lucorum, B. 

 collinus, B. pratorum and some others. 



So much for the British forms of the fly, but it 

 does not confine itself to imitating the colouring of 

 only two kinds of Bombus. Baron Osten Sacken 

 has kindly sent me a copy of a short review by him * 

 of a Russian work by J. Portchinsky on the Diptera 

 of the Caucasus resembling Bombus. M. Portchinsky 

 finds that in the Caucasian mountains the humble- 

 bees (Bombus eriophorus, niveatus, Caucasicus~) are all 

 characterised by the prevalence of white hairs on 

 various parts of the body. The plain black and orange 

 coloured humble bees, like B. lapidarius, are entirely 

 absent. It is therefore remarkable that in this 

 region the black and orange variety of Vohicclla 

 bombylans is absent, as though it had no cause for 

 existing, while in its place a variety ( V. bombylans, 

 var. Caucasica) is found, which is unknown elsewhere 

 in Europe, and in which the thorax and the base of the 

 abdomen are clad with white hairs, after the manner 

 of the humble bees of the Caucasus. A translation of 

 M. Portchinsky's work is much to be desired. 



All entomologists are aware of the great resem- 

 blance which obtains between the hornet clearwing 

 moth ( Trochilium api/ormc) and the hornet ( Vespa 

 crabro). Not less striking is the resemblance to the 

 latter insect of a fly (Milcsia crabroniformis) which, 

 though not found in England, is abundant in many 

 parts of France and Italy. It is exactly the size of 

 an average hornet, the colouring of the thorax 

 abdomen and legs is very nearly the same, while 

 even the wings are of a brownish tinge, similar to 

 that of the hornet's wing. 



* " Wiener Entomologische Zeitung," i. (1882), Heft 9. 



When first I saw one of those flies buzzing round 

 a trellis at Mentone some seven years ago, I captured 

 it under the impression that it was a hornet. 



At Cadenabbia, on the Lake of Como, Milesia 

 crabronifornis was a common insect, and although it 

 was doubtless protected from the attacks of birds by 

 its likeness to a hornet, it sometimes suffered for its 

 resemblance, for I have seen the natives try to kill it, 

 and no amount of explanation could shake their 

 firm conviction that it was a hornet. 



Thus in one family of Diptera we have flies 

 mimicking several types of common Hymenoptera ; 

 the bee, the wasp, the andrena, two forms of humble 

 bee, and the hornet. The similarity is so great in 

 these instances, particularly when the insects are alive 

 and in motion, that no doubt can exist that they 

 are cases of protective mimicry. 



There are, however, other instances of resemblance 

 between Diptera and Hymenoptera on which it is not 

 so easy to decide whether they be cases of mimicry 

 or not. 



Before concluding, I should like to mention two 

 that have come before my notice. Comparing a 

 specimen of Myopa fcrruginea with a species of 

 Nomada (probably N. lateralis), I was at once struck 

 by their general similarity, and remarked that even 

 the whitish patches on the abdomen of Nomada were 

 represented by light spots on the body of Myopa. 

 The likeness between these two insects has pre- 

 viously been observed by entomologists. The other 

 case which occurred to me only just lately, is the 

 resemblance between Mesembrina meridiana and 

 some of the Anthophorae, as A. rctusa. 



The fly, one of the Muscidae, has rather curious 

 colouring, it is entirely black, with the exception of 

 the wings, which, though pale grey towards the tips, 

 are of a brilliant orange-yellow near the base. The 

 Anthophorae are black, but collect a quantity of 

 pollen on their hind legs. They are about the size 

 of M. meridiana. Now is it not highly probable that 

 the yellow at the base of the wings of M. meridiana 

 reproduces, when the insect is flying, the appearance 

 of the pollen on the tibiae of Anthophora ? 



Whether the last two are cases of protective 

 mimicry, could only be ascertained by open-air 

 observation. If the flies are frequently seen asso- 

 ciated with the insects they copy, or are found in 

 similar places and seasons, we may fairly suppose 

 them to be so. With regard to the Myopa, I fancy I 

 have caught it and Nomada near the same spot, but 

 as I knew scarcely any entomology at the time, and 

 was quite a young boy, I may easily be mistaken. 

 Were Diptera studied a little more, we should 

 doubtless find numerous other cases of mimicry among 

 them, including some that are now quite unknown. 

 Let us therefore earnestly hope that some entomolo- 

 gists will employ their leisure in further investigations 

 on this most interesting subject. G. H. Bryan. 



Peter Jwusc, Cambridge. 



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