68 THE HUMBLE-BEE 1 
observations are opposed to those of Hoffer, who 
found the Pszthyrus queen and the Lomdbus queen 
living in the nest on good terms with one another, 
and both of them producing young males and queens. 
But Hoffer’s observations were made chiefly on two 
species of Pszthyrus which I have not been able to 
study, namely, Ps. campestris, which breeds in the. 
nests of B. agrorum and B. helferanus, and Ps. 
guadricolor, which preys on B. pratorum, Evidently 
these species of Bomdus, which, it may be noted, are 
milder tempered than &. lapzdarius and terrestris, do 
not object, in Styria at least, to the Pszthyri laying 
their eggs in their nests. Of course, the Psithyrt, 
in these cases, do not rear so large a family. 
I believe the Pszthyrus queens do not kill one 
another, for I have never found a dead Pszthyrus in 
anest ruled by a Psethyrus. If several Pszthyrz find 
the same nest only one remains, although the others 
may make it their headquarters for a few days, as 
noticed in the above-mentioned nest of B. lapz- 
dartus. 
As might be supposed, the Psz¢hyrus is at first 
very prolific, but she ages and fails more quickly 
than a Gomdus queen. 
The eggs of Ps. vupestris are slightly longer, but 
much more slender, than those of 2. lapidarzus, 
being four times as long as they are thick: the eggs 
of Ps. vestalts are also slenderer than those of 
B. terrestris. 
The development of Psz¢hyrus through the larval 
and pupal stages is the same as that of Bomebus, but 
