The Bumble-Bee Fly 



the white grubs, thanks to the holes that make 

 the wrapper resemble a spongy cover, manage 

 to slip inside the Wasps' nest. Still, most of 

 the Volucella's grubs, at whatever stage of 

 their development, are in the basement of the 

 burrow, among the carrion remains. The 

 others, those settled in the Wasps' home itself, 

 are comparatively few. 



These returns are enough to show us that 

 the grubs of the Bumble-bee Fly do not de- 

 serve the bad reputation that has been given 

 them. Satisfied with the spoils of the dead, 

 they do not touch the living; they do not rav- 

 age the Wasps' nest : they disinfect it. 



Experiment confirms what we have learnt 

 in the actual nests. Over and over again, 1 

 bring Wasp-grubs and Volucella-grubs to- 

 gether in small test-tubes, which are easy to 

 observe. The first are well and strong; I have 

 just taken them from their cells. The others 

 are in various stages, from that of the snow- 

 flake born the same day to that of the sturdy 

 porcupine. There is nothing tragic about the 

 encounter. The grubs of the Bumble-bee Fly 

 roam about the test-tube without touching the 

 live tit-bit. The most that they do is to put 

 their mouths for a moment to the morsel ; then 



265 



