1922] Notes on Nesting Habits of North A merican 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 Bremus terricola ; and (2) the 
well-preserved bodies of a Bremus 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 
Bremus tern cola: 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 a finis. 
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 
