70 THE HUMBLE-BEE 111 
produced, although in a nest containing Ps. vestalis 
I have seen the ¢evvestvzs workers lay their eggs. 
In this same nest, however, I saw the Pszthyrus 
queen calmly eating the workers’ eggs, and I think 
that this is probably the way in which she always 
disposes of them. 
The Pszthyrus queen pays close attention to her 
new-laid eggs for several hours, giving the workers 
no chance to molest them, but the workers soon get 
reconciled to them, and henceforth they feed and 
tend the Pszthyrus brood with as much devotion as 
if it were of their own species: indeed, they seem 
_sometimes to show a greater fondness for it. Hoffer 
found that the larve of Pstthyrus campestris died 
in a case where the Pse¢thyrus queen disappeared 
while they were still very young, and concluded 
that the Pszthyrus contributes something essential 
to the nourishment of her larve when they are 
young. I have seen a queen of Ps. dstinctus, a 
species closely allied to Ps. vestatis, feeding her 
young larvee; but some later larve of this queen 
developed into fair-sized queens, although I removed 
her when they were very small, namely, twenty-five 
days before the queens emerged. 
The hard, convex, narrow and naked underside 
of the abdomen of the Pszthyrws queen is unsuited 
for incubating, and I have never seen her spreading 
herself over the brood. 
On July 14, 1911, I took a nest of B. hortorum 
containing its parasite Pszthyrus barbutellus. There 
were 49 hortorum workers, many with shiny 
