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. 



T 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 T 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 T 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. T found among the partitions built by the 



*This mav be due to the scarcity of redwood in this vicinitv. 



