Squash bee

The name Squash bee is applied to two related genera of bees in the tribe Eucerini; Peponapis and Xenoglossa. Both genera are oligoleges (pollen specialists) on the plant genus Cucurbita and closely-related plants (squash, cucumbers, etc.). They are small genera, containing only 13 and 7 described species, respectively, and their combined range is nearly identical to the range of Cucurbita in the New World, from South America to North America. Their range has become somewhat expanded along with the movement of cucurbits into other areas (as crop plants). The bees themselves are of moderate size, equal to various bumblebees. The pollen-carrying hairs on their legs (the scopa) are unbranched or nearly so, and sparse, to accommodate the exceptionally large, coarse pollen of the host plants. They have also evolved a matinal daily activity cycle, flying before sunrise. Some Xenoglossa species have become morphologically specialized to fly while it is still dark, with greatly enlarged ocelli to allow them to fly in near-darkness.

The two genera are sometimes thought to be sister taxa, but there are enough differences between them to suggest that the similarities may be due to convergent evolution, based on their adaptation to utilize the same host plants.