1922] Notes on Nesting Habits of North American Bumblebees 197 
# 
started between the middle of May and the middle of June. The 
workers begin to appear about the first week of June, and the 
majority of the young queens and males hatch in August and 
September. The workers may be seen foraging as late as 
October. 
Bremus impatiens is one of the more vicious species. 
I IT. Bremus vagans Smith. 
A nest of this species was discovered by Putnam (1865, p. 98) 
in 1862 at Warwick, Mass., but it is not clear from his description, 
whether it was situated in an old stump or under a pile of stones. 
A nest taken by Beutenmuller (cf. Franklin, 1912/13, I, p. 354), 
at Potato Knob, North Carolina (elevation 6,420 ft.), about 
July 1, 1902, was situated in a hollow tree, and contained 2 
queens and 8 workers, but several individuals escaped. A third 
nest, taken by Franklin (1912/13, I, p. 354) July 20, 1904, on 
the surface of the ground, contained 2 queens, 2 males, and 8 
workers. 
I took 6 nests of this species in, or near, the Arnold Arboretum 
during the summers of 1921 and 1922. Two of these were sur- 
face nests, while the remaining 4 were subterranean. The latter 
were all about a foot below the surface of the ground and had 
tunnels varying from 1 to 5 ft. in length. The largest nest con- 
tained (August 2, 1921) the old queen, over 70 workers, and a 
considerable quantity of brood. This colony, as has been stated 
in another paper (1922), was later victimized by a Psithyrus. 
In addition to the nest just mentioned, 2 others were para- 
sitized by Psithyri. One of these was taken June 26, 1922. It 
contained (1) the old queen and about 40 workers of Bremus 
vagans ; and (2) a Psithyrus queen belonging to the Laboriosus 
Group. The other, taken July 20, 1922, consisted of (1) the 
old queen and 6 workers of Bremus vagans ; and (2) a Psithyrus 
queen belonging to the Laborisous Group. From one of these 
two colonies a considerable number of Psithyrus males and 
several Psithyrus females were reared which are different from 
those obtained from the Bremus impatiens nest referred to above. 
