194 
Psyche 
[December 
Nests of D. pudicum, although not very rare, are rather 
difficult to find, because of the fact that they often closely re- 
semble in color the rock to which they are attached. Again, 
they may fill in a depression, giving the rock a smooth outline 
and therefore easily overlooked. Many fields, in which these 
bees nest, are nearly covered with rocks and the task of finding 
the ones used is great. However, a bee sometimes selects a very 
light or white rock and builds upon it a nest consisting of dark 
pebbles. 
When the weather is dry, the pebbles and resin become very 
hard and the nest is difficult to remove. Rain or very moist 
weather softens the material and may aid in making it easier for 
the mature insect to emerge. 
The number of cells to a nest have varied from 2 to 8. A 
cocoon, which appeared to be of average size, measured 9 mm. 
in length from the tip of the mammillary projection to the base 
of the cocoon. The width at the center was a little over 4 mm. 
The base is slightly curved; the apex flat except for a short, 
blunt mammillary point. This point was much lighter than the 
dark, yellowish brown cocoon. 
Observations were made on the habits of a bee of this species 
found nesting on a rock at Owens’ Lake, late in the afternoon 
of August 24, 1926. When located one cell had already been 
constructed, with the orifice down. This opening was clear cut, 
or sharply and very neatly outlined. At 6 p. m. the female was 
resting within, where she spent the night, with the posterior 
part of her body towards the outside. Some data were obtained 
on following days, part of which are given below. 
August 25. By 11a. m. the orifice of the first cell was closed 
and a second had been started. The bee was now carrying resin 
and pebbles to the nest. Later, when she was walking over it 
slowly, as though inspecting it, a male came and mated with her 
on the finished cell. The period of copulation was of about 30 
seconds duration. 
August 27. The bee was observed flying about in the 
morning, probably gathering honey. 
August 31. To-day, the fourth cell has been made. The 
place and order of occurrence had been noted on previous days. 
