1. Department of Fisheries and Wildlife Oregon State University Corvallis OR 97330 U.S.A.
2. Hermiston Agricultural Research and Extension Center Oregon State University Hermiston OR 97838 U.S.A.
3. United States Forest Service Pacific Northwest Research Station La Grande OR 97850‐3368 U.S.A.
4. Bee Biology and Systematics Laboratory Utah State University Logan UT 84322 U.S.A.