208 
BRITISH BEES. 
the birds, thrives at the expense of the young of the 
sitos by consuming its food, and thus starving it. These 
parasites consist of many of the species of Nomada, 
very pretty and gay insects, but in every case totally 
unlike the bee whose nest they usurp. Several of the 
species of these Nomada are not limited to any particu¬ 
lar species of Andrena, but infest several indifferently, 
whereas others have no wider range in their spoliation 
than one single species, to which they always confine 
themselves. In my observations under the genus No¬ 
mada I shall notify those which they assail amongst the 
Andrena , as well as the other genera which they also 
infest. 
The others which attack them are more properly po¬ 
sitive enemies than parasites, for they prey upon the 
bees themselves, or, as in the case of the remarkable 
genus Sty lops, render the bee abortive by consuming 
its viscera and ovaries. I have spoken of these insects 
in the chapter upon parasites, to which I must refer, 
but I may here add that the female is apterous, and 
never quits the body of the bee. Much mystery at¬ 
taches to their history in which their impregnation is 
involved, for the male, immediately upon undergoing its 
change into the imago, escapes through the dorsal plates 
of the abdomen of the bee wherein it was bred and 
takes flight. In localities where they occur they may 
be usually taken on the wing in the month of May. 
The female would seem to be viviparous, and produces 
extraordinary multitudes at one birth, extending to hun¬ 
dreds. Being born as larvae within the body of the 
bee they seek to escape from their confinement, and find 
the opportunity in the suture which separates the meso- 
thorax from the metathorax. Their extreme minuteness 
