160 Journal of Entomology and Zoology 
her task, but she had advanced less than one inch. Fig. 1 shows this 
tunnel and the rate of progress. It seemed to be a typical case. 
I have known one tunnel to be several weeks under construction. 
Their average length is from four to six inches. Those of greater 
distance, I think, are the result of more than one season’s work, 
having been lengthened from year to year. 
While digging, the bee slowly turns in the burrow, requiring from 
thirty minutes to an hour to complete the cycle. Observation 
showed no regularity or uniformity either in rate or direction of 
turning. 
I have never found orpifex except in reasonably large aggrega- 
tions. If some adventurous female begins work in a new locality, 
that locality is sought out by others until almost every available 
timber is honey-combed with tunnels*. From one surface entrance 
there are usually several tunnels leading away. Figs. 8 and 9 are 
typical in this respect. This habit doubtless serves well in the reduc- 
tion of labor and also reduces the danger from enemies. A third 
advantage gained is the mutual protection against changes of tem- 
perature during the winter, for I found these tunnels, on cold days, 
literally packed full; in many cases two rows of bees lying side 
by side in the same tunnel. 
Other than the points mentioned I find no hint of true community 
life. Males and females are about equal in number, and in the 
rearing of young they behave as other solitary bees so far as I am 
able to learn. No food is stored for winter but on warm days 
they come forth in search of food, a temperature of about 20 deg. 
to 21 deg. C. being sufficient to invite them out. 
Life History: Having finished her tunnel the female begins to 
provision it with bee-bread which she makes from pollen and regur- 
gitated nectar. After accumulating a mass about as large as her 
own body she lays an egg upon it and walls up that part of the bur- 
row with a partition of chips of wood cemented together in the 
form of a spiral (Fig. 2), as Comstock has described in the case 
of Xylocopa virginica. Examination showed no uniformity in the 
direction of this spiral. I found among the partitions built by the 
*This may be due to the scarcity of redwood in this vicinity. 
