84 THE CANADIAN ENTOMOLOGIST 
INQUILINE BUMBLE-BEES IN BRITISH COLUMBIA. 
BY F. W. L. SLADEN, APICULTURIST, CENTRAL EXPERIMENTAL FARM, 
OTTAWA. 
Having been informed by Mr. R. C. Treherne of a nest of 
bumble-bees in his garden at the foot of the mountain at Agassiz, 
B. C, I dug it up on July 7, 1914. The nest was found at about 
18 inches from the surface. It contained an old queen of Bombus 
flavifrons and about half a dozen workers of the same species; 
also the well-preserved body of a female of Psithyrus insularis Sm., 
and several unopened cocoons, out of one of which I extracted a 
male, nearly ready to hatch, of Psithyrus consul tics Frank. The 
occurrence of Psithyrus in this nest is of considerable interest, 
for Franklin said in his recent monograph of the Bombidae of 
North America (Trans. Am. Ent. Soc. XXXV, page 448), "There 
is not yet a single new world account of a Psithyrus having been 
found in a bumble-bee's nest." 
Moreover, several noteworthy conclusions are indicated. 
Corroboration of a new and highly convincing kind is given 
to the already well-founded belief (id., page 458), that consuUus 
is the male of insularis, for the female insularis was in all probability 
the mother of the male consnltns. It may be remarked that the 
name insularis has priority. 
Second, Ps. insularis is evidently parasitic upon B. flavifrons 
in British Columbia. In Eastern Canada {insularis is common at 
Ottawa) it must prey upon some other species of Bombus, for 
flavifrons is not found in the east. Probably, however, it lives 
with several species in both regions. 
Third, Ps. insularis does not apparently kill the Bombus queen, 
as I have found Ps. vestal is and rupestris do in England ('"The 
Humble Bee," page 60), but both females seem to live together in 
the nest, laying eggs. (The death of the insuralis female was 
evidently due to age or accident.) This seems to be in accord 
with Hoffer's observations on Psithyrus campestris, the Old World 
representative of insularis. He found Ps. campestris living on 
good terms with its hosts, B. agrorum and helferaniis, both queens 
producing young (Die Schmarotzerhummeln Steirmarks, page 101). 
March, 191o 
