Technical Abstract: Males can comprise a substantial fraction of the bees that visit flowers, particularly at floral hosts of those bee species that are taxonomic floral specialists for pollen. Despite their prevalence in a number of pollination guilds, contributions of male bees to host pollination have been largely overlooked or ignored. In this study, males of the squash bee Peponapis pruinosa Say are shown to be effective pollinators of summer squash, Cucurbita pepo L. Seven sequential visits from male P. pruinosa maximizes squash fruit set and growth rate. This visitation intensity is readily achieved within their first hour of morning foraging and mate searching. Male pollination efficacy and their abundances at squash flowers were sufficient to account for most summer squash production at our study sites, and by extrapolation, to 2/3 of all 87 farms and market gardens growing squashes that were evaluated by collaborators in the Squash Pollinators of the Americas Survey.