204 THE HUMBLE-BEE VIII 
and is very helpful in distinguishing them from one 
another. 
The coat is less dense than in the Bomdus queens, 
the hair being particularly scanty on the abdomen, 
at 




ny Dy! Ae hil 
fr Myihn AWTR 
(i A / a } 
A sua 
2S ie 
Ps. distinctus Ps. quadricolor 

Fic. 30.—Tip of the abdomen (underside) of the queen of each of the British 
species of Psithyrus, showing the elevations on the 6th ventral segment. 
which in the middle looks almost bare; also the 
hairs are somewhat coarser than in Lomedus. 
Psithyrus queens usually have their wings more 
clouded than Bomdbus queens, and they may generally 
be recognised in the field by their weaker flight with 
its distinctly lower-pitched and softer hum. 
