1927] 
Nesting Habits of a Solitary Bee 
199 
NESTING HABITS OF A SOLITARY BEE OF THE 
GENUS SPINOLIELLA OF ASHMEAD 1 
By Clarence P. Custer, 
University of Colorado, Boulder, Colo. 
The nests of the bees of this genus are generally hard to 
find. The insects are so small, usually not more than a quarter 
inch long, that they are difficult to follow in their flight. In 
fact, so far as I can tell, no information is available on their 
nesting habits. 
It was on a fine sunny day in the latter part of August, 
1927, while visiting the Country Club at Denver, Colorado, 
that my attention was called to some small mounds of dark soil 
resembling ant nests. These were located along the side of a 
tennis court. It was soon evident that they were the nests of 
some bees. They had picked three different areas in which to 
establish their dwellings. Each colony possessed some forty or 
fifty nests separated from one another by a distance of about six 
inches. 
Each day the courts had been moistened and rolled by the 
caretaker. And each day the busy owners had thrown up the 
small mounds of soil over their entrances. When I arrived, 
the colonies were bustling with work. Here was a bee opening 
the entrance to her nest. Up the tunnel she backed, pushing a 
load of earth. When almost to the top, she suddenly stopped 
and descended for another load. The earth in the entrance-way 
remained without falling. Presently she was up again with 
some more. This was also pushed out of the entrance a portion 
remaining in the passage-way as before. The little mound of 
soil above the nest was steadily increasing in size. Over here 
was a female just in from the fields. Her hind legs were heavy 
and quite conspicuous with their loads of green pollen. Back 
and forth she circled, undecided which of the nests was her own. 
Several times she alighted on the ground. After a minute, the 
problem solved, she hovered over her nest and entered. In other 
1 Spinoliella australior Ckll. Determined by Miss Grace Sandhouse. 
