SOME OBSERVATIONS ON THE LIFE HISTORY AND HABITS OF 
PARASITIC BEES. 
BY S. GRAiHNICHER. 
We are rather poorly acquainted with the habits of those bees, 
that lay their eggs in the nests of other bees, instead of construct- 
ing nests of their own. They figure under the name of inqui- 
lines or guest-bees, while the rightful occupants of the nests are 
called host-bees. Some writers invariably make use of the term 
"parasitic bees" when referring to guest-bees in a general way, 
although in at least one instance the larva of the guest-bee has 
been observed as a commensal in the nest of the host-bee, and 
not as a parasite. Our knowledge is especially deficient in re- 
gard to the fate of the egg or larva of the host-bee after one 
or more eggs of the guest-bee have been placed in the same cell 
together with the egg of the host-bee. In this respect I have 
been able to gather the following information from the literature. 
Packard, (1), in referring to nests of Andrena and Halictus, col- 
lected at Salem, Mass., by J. H. Emerton, states that both sexes 
of Nomada imbricata Sm., and several females of Nomada 
pulchella Sm., were found in the nests of Andrena vicina Sm., 
as also some specimens of Nomada imbricata in the cells of 
Halictus parallelus Say. According to Packard "there seems to 
be enough for both genera to feed upon, as the young of both 
host and parasite were found living harmoniously together, and 
the hosts and their parasites are disclosed at the same time." 
Concerning the relations between the bumble-bee and its 
guest-bee Psithyrus I copy from Sharp, (2), the following. "The 
Bombus and Psithyrus live together on the best terms, and it 
appears probable that the latter do the former no harm bevond 
appropriating a portion of their food supplies. Schmiedeknecht 
says they are commensals, not parasites." Farther on Sharp re- 
marks: "The cells in which the young of the Psithyrus are 
hatched are very much larger than those of the Bombus and it 
may therefore be presumed are formed by the Psithyrus itself." 
Fabre, (3), has come across from 2 to 12 eggs of the guest-bee 
Stelis nasuta in the nest of the much larger mason-bee Chalico- 
doma muraria. The several larvae of Stelis nasuta live frater- 
1. A. S. Packard. Guide to the Study of Insects, 6th Ed. (1878), 
p. 142. 
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