Unequal Cellophane Bee (Colletes inaequalis)

On a early spring walk this morning we came across these bees swarming about some bushes. On closer inspection, there were dozens, probably a hundred, of these small bees flying low on the ground.

After a lot of patience, we were able to photograph a few on the ground. It turned out that these bees were small little "cellophane" bees of the genus Colletes.

"Female cellophane bees carry pollen on the upper part of their hind legs"
After some research, I believe these are Colletes inaequalis, an early spring emerging species which nest in the ground. They line their burrows with a polyester-like substance for which they get their common name. Below you can see one of their burrows, it looks like an anthill but with an oversized hole for an entrance. It turns out that both the females and males make their own burrows. There were many, many of these burrows in the loose soil and sand patches between the grass.

Here is a female and a male. The male is the smaller one.

This species is an important early pollinator and are not aggressive (unlike some ground-nesting wasps when disturbed). Colletes feed on maple blossoms and help pollinate certain berry species.

Here is a female bee defending her burrow. The males are about half the size and have a hairy head. This was a new species of bee for me. Be on the lookout for this species for another month in its range.

A defiant female poking out of her nest.
Source I used for information.