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. 



III. Br emus 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 Beutenmiiller (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. 



