The Bamble-Bee Fly 



repeatedly brush against and stride across the 

 Volucella-grub. There is no doubt that they 

 see it. The intruder does not budge, or, if 

 trodden on, curls up, only to reappear the 

 next moment. Some of the Wasps stop, bend 

 their heads over the opening, seem to be mak- 

 ing enquiries and then go off, without troub- 

 ling further about the state of things. One of 

 them does something even more remarkable : 

 she tries to give a mouthful to the lawful occu- 

 pant of the cell ; but the larva, which is being 

 squeezed by its visitor, has no appetite and 

 refuses. Without the least sign of anxiety 

 on behalf of the nursling which she sees in 

 awkward company, the Wasp retires and goes 

 to distribute its ration elsewhere. In* vain I 

 prolong my examination : there is no fluster 

 of any kind. The Volucella-grub is treated as 

 a friend, or at least as a visitor that does not 

 matter. There is no attempt to dislodge it, to 

 worry it, to put it to flight. Nor does the 

 grub seem to trouble greatly about those who 

 come and go. Its tranquillity tells us that it 

 feels at home. 



Here is some further evidence : the grub has 



plunged, head downwards, into an empty cell, 



which is too small to contain the whole of it. 



Its hind-quarters stick out, very visibly. For 



271 



