1922] Notes on Nesting Habits of North American Bumblebees 193 



a tunnel 1 ft. long; the other, according to Dr. Anderson, was 

 about 3 ft. below the surface, and had a tunnel 21 ft. long. The 

 nest taken near the Arnold Arboretum contained (1) 9 young 

 queens and about 60 workers of Brenins terricola; and (2) the 

 well-preserved bodies of a Bremns impatiens and a Psithyrus 

 queen belonging to the Laboriosus Group. In the other, Dr. 

 Anderson found (1) the old queen and about 125 workers of 

 Br emus terricola: and (2) numerous pseudo-scorpions. 



In the vicinity of Boston, Bremus terricola is the first bumble- 

 bee to appear in spring. In 1922 several queens were seen on 

 willow as early as April 13th. Most colonies are probably 

 started between the 15th of April and the 15th of May. The 

 workers begin to appear shortly after the middle of May, and 

 most of the young queens and males are produced in July and 

 August. I have never seen any workers after September 1st. 



The workers of Bremus terricola are somewhat more vicious 

 than those of Bremus affinis. 



BoREALis Group. 



I. Bremus borealis Kirby. 



Coville (1890, pp. 198,201) records taking a nest of this 

 species in July 1885 near Ithaca, N. Y. It contained "the queen 

 and a large number of workers," but nothing is said as to whether 

 the nest was situated on, or below, the surface of the ground. 



On July 8, 1922, I noticed a Bremus borealis queen searching 

 for her nest among the mowed grass near a stump, about a mile 

 from the Arnold Arboretum. She was carrying a big load of 

 pollen and repeatedly arose into the air to take her bearings. 

 Whenever she alighted, she hurriedly crept about among the 

 grass, at times frantically shaking her wings. I removed all 

 the cut grass within a radius of about 10 ft. of the stump, but 

 even then she was unable to find her nest. Fearing that she 

 might desert the place, I captured and used her for breeding 

 experiments which will be described in a separate paper. Although 

 I searched carefully near the stump, no surface nest 



