Species such as Peponapis pruinosa have been in decline due to several reasons, probably at least in part to pesticide sensitivity.

Compared to honeybees, squash bees are larger and bulkier, with longer antennae and rounder faces.

[3] The pollen-carrying hairs on their legs (the scopa) are unbranched or nearly so, to accommodate the exceptionally large, coarse pollen of the host plants.

[3] Squash bees have also evolved a matinal daily activity cycle, flying before sunrise.

[citation needed] The two genera are sometimes thought to be sister taxa, but enough differences occur between them to suggest the similarities may be due to convergent evolution, based on their adaptation to use the same host plants.