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occupant. Examination of the combs shows a 

 large number of grubs of all sizes engaged in this 

 work. These remarks apply to Volucella pellucens, 

 which we have found so engaged in the underground 

 nests of Vesfa germanica, a common wasp. Other 

 species are attached to other species of wasps and 

 to distinct species of Humble Bees. 



The best-known species of Volucella is V. homby- 

 lans, whose hairy body has a general resemblance 

 to a Humble Bee, and it is interesting to note 

 that in early life it lives in the nests of various 

 species of Humble Bees. In former days, not 

 long ago — when these flies were regarded as para- 

 sites — the resemblance to a Humble Bee was held 

 to have been acquired specially to enable it to 

 enter the bee's nest to lay eggs without its real 

 character being suspected ; but, seeing that Volu- 

 cella pellucens does not resemble a wasp in the 

 remotest manner, this theory will not hold good, 

 for this species should stand more in need of such 

 protection than F. bombylans, because the wasps 

 prey very largely upon the two-winged flies, whilst 

 Humble Bees are not insectivorous at all. 



However, mimetic resemblance does not come 

 within the scope of our present inquiry. The 

 grubs of F. bombylans clean out the vacated cocoons 

 of the Humble Bees and make them available for 

 the storage of pollen ; they also eat up the debris 

 that collects under and around the irregular comb, 

 and so help to keep the nest sweet. 



