1916 Pomona College of Entomology and Zoology, I ol. I III, No. 4, December 



Studies in the Life Histories of Two Car- 

 penter Bees of California, With 

 Notes on Certain Parasites 



II. II. NININGER 



Xylocopa orpifex Smith 



Systematic observation of this species was extended over a period 

 of one year, beginning September 29, 1915. 



Methods: The colony chosen for study is located on the sum- 

 mit of a small mountain rising from San Dimas Canyon of the San 

 Gabriels, at an altitude ol about 3,500 feet, where it occupies the 

 timbers of a small, deserted cabin. It required two hours of climb- 

 ing to reach the cabin from the foot of the mountains. About six- 

 teen trips were made at intervals during the whole autumn, winter 

 and spring and one in late summer. Pieces of timber were brought 

 to the laboratory from time to time, and opened. During the breed- 

 ing season those occupied by eggs or larvae were carefully preserved 

 and prepared for daily observation by splitting the timber so as 

 to expose the contents of the cells when the parts were separated, 

 and again refitting the parts and holding them in place by means of 

 clamps when not under observation; or, by smoothing the split sur- 

 face and carefully fitting a piece of glass over the opened cells, 

 which was then held in place by means of glue or other paste. In 

 one case a tightly-fitting sliding glass plate was used quite success- 

 fully. A dark cover of some kind was kept over the glass, except 

 during observation, thus preserving as nearly as possible the natural 

 conditions. As a check on the whole study a trip to the cabin was 

 made at the season of their emergence and a number of cells were 

 opened which seemed to corroborate all of the conclusions reached 

 from the experiment, except in the case of certain parasites as noted 

 below. 



Habits: Orpifex shows a decided preference for redwood as a 

 medium in which to burrow. Though I found them, in one or two 

 cases, using Oregon pine. It shows no inclination to choose decay- 



