1982] 
Torchio & Tepedino — Osmia Bees 
223 
Figure 1. Percent of total offspring of O. montana (a) and O. californica (b) that 
were one-year forms (solid lines), and males (dashed line) at two northern Utah 
sites over two years. Dotted and dashed line represents the expected sex ratio as 
percent males. 
mg) and all individuals were then inserted into clear, #000 gelatin 
capsules. Capsules were then placed in a constant 4 degrees C 
temperature cabinet on September 30 of each study year and trans- 
ferred to a 26 degrees C temperature cabinet on June 1 of the 
subsequent year. A photoperiod of OL:24D was maintained 
throughout these treatments. Capsules containing two-year forms 
(now adults) were removed from the temperature cabinet on August 
30 and reweighed. 
Results 
Osmia montana 
Almost 1 100 nests were available for examination from the four 
site-years of sampling (Table 1). Nest utilization was higher in 1979 
than in 1980 at both sites, and higher at Faust than at Mendon in 
both years. 
There were differences between sites and years in the proportion 
of offspring that were one-year forms (Fig. la). At Faust a signifi- 
cantly higher proportion of one-year forms was produced in 1979 
