500 DIPTERA CHAP. 



possibility of a favourable result. It was certainly not bees that 

 were produced from the carcases, but Osten Sacken suggests that 

 JBristalis-Qiea may have been bred therein. 



In the genus Volucella we meet with a third kind of Syrphid 

 larva. These larvae are pallid, broad and fleshy, surrounded by 

 numerous angular, somewhat spinose, outgrowths of the body ; 

 and have behind a pair of combined stigmata, in the neighbour- 

 hood of which the outgrowths are somewhat larger ; these larvae 

 live in the nests of Bees and "Wasps, in which they are abundant. 

 Some of the Volucella, like many other Syrphidae, bear a con- 

 siderable resemblance to Bees or Wasps, and this has given rise to 

 a modern fable about them that appears to have no more legiti- 

 mate basis of fact than the ancient Bees-born-of-carcases myth. 

 It was formerly assumed that the Volucella-la,rva,e lived on the 

 larvae of the Bees, and that the parent flies were providentially 

 endowed with a bee -like appearance that they might obtain 

 entrance into the Bees' nests without being detected, and then 

 carry out their nefarious intention of laying eggs that would 

 hatch into larvae and subsequently destroy the larvae of the Bees. 

 Some hard-hearted critic remarked that it was easy to understand 

 that providence should display so great a solicitude for the welfare 

 of the Volucella, but that it was difficult to comprehend how it 

 could be, at the same time, so totally indifferent to the welfare of 

 the Bees. More recently the tale has been revived and cited as 

 an instance of the value of deceptive resemblance resulting from 

 the action of natural selection, without reference to providence. 

 There are, however, no facts to support any theory on the subject. 

 Very little indeed is actually known as to the habits of Volu- 

 cella in either the larval or imaginal instars ; but the little that 

 is known tends to the view that the presence of the Volucella 

 in the nests is advantageous to both Fly and Bee. Nicolas has 

 seen Volucella zonaria enter the nest of a Wasp ; it settled at a 

 little distance and walked in without any fuss being made. Erne 

 has watched the Fb/wceZ/a-larvae in the nests, and he thinks that 

 they eat the \vaste or dejections of the larvae. The writer kept 

 under observation Fbwce//a-larvae and portions of the cells of 

 Bombus, containing some larvae and pupae of the Bees and some 

 honey, but the fly-larvae did not during some weeks touch any of 

 the Bees or honey, and ultimately died, presumably of starvation. 

 Subsequently, he experimented with Volucella-lavvde and a portion 



