VIII SRE NIEOS “CAM PES TRIS 217 
Antenne long ; length of flagellum 64 mm. The 4th 
joint of the antenne is very slightly shorter than the 3rd: 
the 5th joint is almost as long as the 3rd and 4th 
together. 
Armature distinct. 
A light male from Chobham, Surrey, in the Saunders’ Collection, 
has the whole 2nd segment yellow with the exception of a few black 
hairs on its sides. 
Ps. campestris is widely distributed in England, 
Wales, Ireland, and Scotland, and common in a few 
places. In the Dover district it is seldom seen. 
Most authors state that it is parasitic on JB. 
agrorum, and its distribution points to this. In 
Styria, Hoffer found it breeding in the nests of 
B. agrorum and LB. helferanus. 
Ps. campestris, like Bombus ruderatus, is subject 
to colour dimorphism, most examples being either 
very light or very dark. 
Judging by the large number of specimens I 
have seen in Irish collections this is the commonest 
species of Pszthyrus in Ireland. In the lightest 
Irish specimens the thorax is yellow with the ex- 
ception of a few black hairs in the centre. None of 
the numerous black specimens of both sexes from 
Ireland that I have seen have lacked yellow, or a 
trace of it, on the tail. 
