1922] Notes on Nesting Habits of North American Bumblebees 191 



largest colony was taken on September 1, 1922. It contained 

 the old queen, 19 young queens, 27 males, and over 175 workers. 



Not long ago, Bequaert (1920) described a new variety of 

 Bremus affinis which he called novce-anglice. This variety oc- 

 curred in 2 of the 8 nests mentioned above. The first of these 

 was taken July 11, 1922. It contained (1) the old queen, 1 

 young queen, and 43 workers of Bremus affinis; (2) 12 workers of 

 Bremus affinis var. novce-anglice; and (3) 1 worker of Bremus 

 terricola Kirby. The second nest was taken August 4, 1922. 

 In it were found (1) 23 workers of Bremus affinis; (2) 9 workers 

 of Bremus affinis var. novcc-anglice; and (3) 1 worker of Bremus 

 terricola. The contents of these two nests, and the character 

 of the bees reared from the second, suggest that Bremus affinis 

 var. novce-anglice Bequaert is a hybrid between Bremus affinis 

 and Bremus terricola, a question which wiW be discussed in an- 

 other paper. 



Tvv'o other of the 8 Bremus affinis nests were victimized 

 by Psithyrus ashtoni Cresson. One of these, on August 9, 1921, 

 contained (1) the old queen and about 100 workers of Bremus 

 affinis; and (2) the old queen, 3 young queens, and 6 males of 

 Psithyrus ashtoni. A detailed account of the subsequent history 

 of this affinis-ashtoni colony has appeared in another paper 

 (1922). The second colony parasitized by Psithyrus ashtoni 

 was taken on July 26, 1922. It contained (1) the old queen and 

 about 20 workers of Bremus affiiiis; and (2) the old queen (dead), 

 2 young queens, and 2 males of Psithyrus ashtoni. During the 

 following weeks several more young Psithyrus queens and males 

 were obtained from this colony. 



Bremus affinis frequently stores a considerable quantity of 

 pollen in long, waxen cells, which Hoffer (1882/83, II. pp. 85, 86) 

 called pollen cylinders. I noticed a number of these pollen 

 cylinders in 2 of the 8 Bremus affinis colonies. Both of these 

 colonies were rather large, each one having over 150 workers. 

 In one of these two nests most of the pollen cylinders were from 

 5 to 6 cm. long, and tlie total pollen contained in them weighed 

 about 2 ounces. 



