76 THE HUMBLE-BEE 



is not always the larvae in the largest cocoons that 

 are victimised. The maggots usually creep into the 

 nest material to pupate : the puparium is at first 

 yellowish -brown, afterwards it becomes dark red. 

 The perfect flies emerge in two or three weeks ; 

 they may be easily obtained by placing the pupae in 

 a glass jar and covering it with muslin. 



A very interesting dependant on the humble-bee 

 is the large fly, Volucella bombylans. This hand- 

 some insect is about the size of a worker humble- 

 bee and superficially resembles it closely, being of 

 a stout build and covered with long hair which in 

 some specimens is red at the tail and black over the 

 rest of the body in imitation of B. lapidarius and 

 B. derkamellus, and in others is white at the tail 

 and marked with yellow on the thorax and base of 

 the abdomen in imitation of the white-tailed, yellow- 

 banded species, particularly B. jonellus and B. 

 hortonmi. Both forms occur plentifully in most 

 districts and have, I believe, been bred from the 

 same parent. But the mimicry of Volucella does 

 not end here. It is very fond of sunning itself upon 

 flowers frequented by humble-bees, such as the heads 

 of the greater knap- weed (Centaurea scabiosa), and 

 if a specimen be grasped in the fingers it makes a 

 buzzing noise so exactly like a humble-bee that the 

 fear of getting stung makes one feel inclined to drop 

 it instantly. Moreover, these Hies hover about over 

 grassy banks, etc., in the same manner as a Bombus, 

 searching for humble-bees' nests in which to lay 

 their eggs, and at a distance I have often mistaken 



