Abstract
Examination of old Sceliphron jamaicense (Fabr.) nests at 4 localities near the tip of the Baja California peninsula showed levels of brood success (i.e., the fraction of fully provisioned, closed cells producing viable adult offspring) between 24.6% and 58.1% per site. Failure was predominantly at the pupal stage at all localities. Successful cells are commonly reutilized by other solitary wasps, primarily Trypoxylon (Trypargilum) dubium Coville and Chalybion californicum (Sassure, 1867). There is a pronounced clumping tendency in successes and failures among nests.