190 Psyche [October-December 



several others. A brief resume of all that is known of the nesting 

 habits of the 9 species treated in this paper has been added, in 

 order to make these data as complete as possible. The new 

 facts which I have recorded in the following paragraphs are 

 based on observations of 55 bumblebee colonies which were 

 discovered at Berkeley, Calif., Washington, Me., and Boston, 

 Mass., during the summers of 1920, 1921, and 1922, and on 

 copious field notes. 



The interesting beetles of the genus Antherophagus, and 

 also mites of the family Gamasidai, occurred in almost every one 

 of the 50 nests which I examined, and in one case over 20 of the 

 beetles were found; but, to avoid useless repetition, the individual 

 cases are not cited below. 



Terrestris Grottp. 



I. Bremus affinis Cresson. 



Very little is known concerning the nesting habits of this 

 bee. Some years ago, Franklin (1912/13, I, p. 280) found a 

 nest in southern Vermont during the early part of July. It 

 was situated in an open mowing place on the surface of 

 the ground, and. since it contained but a few cells with par- 

 tially developed larvae, had apparently been started only shortly 

 before by the queen. Franklin (p. 280) makes the following 

 statement regarding the location of this nest: "Although this 

 was a surface nest, the fact that the queens of this species are 

 never seen in abundance, while the workers and males in late 

 summer often appear in large numbers, together with the fact 

 that their nests are so seldom found, leads me to the opinion 

 that they are usually subterranean." 



The surmise expressed in the forgoing quotation is confirmed 

 by my own observations. Of 9 Bremus affinis nests discovered 

 in the Arnold Arboretum (within the city limits of Boston) 

 during the summers of 1921 and 1922, every one was subterranean. 

 They were situated from 1 to 4 ft. below the surface of the ground 

 and had tunnels varying from 18 inches to 8 ft. in length. The 



