A DREADFUL PARASITE 79 



tance, and can only crawl about, or perhaps 

 take short flights of a foot or so. The effects, 

 however, seem to be very different in different 

 cases. I have caught Andrenas with two Stylops 

 in them, flying about as usual and apparently 

 none the worse for their inmates. Probably 

 the position the parasite occupies may make 

 a great difference in its effects on the bee. 



The most notable effect produced by Stylops 

 is the alteration in the structure and colour of 

 certain of the bee's characteristic features. In 

 Andrena the males differ very considerably 

 from the females both in form and colouring. 

 They have no pollen-brushes on their legs, and 

 in some few species the face above the mouth 

 is white, whereas in the female it is black. Now 

 the effect of the parasite seems to be to unsex 

 as it were its victims so far as their outward 

 appearance is concerned. This is no doubt 

 due to the internal effects it has on the larva of 

 the bee. Anyhow, if a female is attacked, in most 

 cases the pollen-brush is much reduced, the face 

 tends to become more hairy, and, if it be the 

 female of a white-faced male, spots of white are 

 often produced on the face. On the other hand, 



