Cellophane Bees

Cellophane bees are among of the very first pollinators to emerge in spring in Wisconsin - these bees surface right after the last March snows begin to melt, when the weather is still chilly.

The bees remain visible for only a brief period, usually through the end of April.

  Description

There are about 100 species in the genus in North America. They’re found in prairies and lawns, on embankments and woodland edges, and in other places where the soil is easy to excavate.

Cellophane bees are solitary bees, unlike the very social ants and Honey Bees, although they are comfortable surrounded by the nests of their sisters (nest aggregation). Sometimes they are surrounded by hundreds or thousands of Cellophane Bees.

These bees line their nests with a glue-like substance which creates a thin, cellophane-like membrane - hence the name cellophane bees.

Cellophane Bees have heart-shaped faces with big eyes that angle out (instead of being parallel), and pale stripes on their abdomens. They are fuzzy with pollen-collecting hairs on their back legs.

  Nesting

Like other ground-nesting bees, female cellophane bees dig tunnels or she sometimes reuses and enlarges old tunnels, making a separate cell for each egg. She digs by biting the soil with her mandibles, aided by vibrations from her flight muscles. She uses her second and third pairs of legs to muscle the dirt out of the tunnel.

Because she is equipped with two special glands, one fore and one aft, she can build a better nest. First, she spreads saliva over the inside of the cell with a short, two-lobed, fringed tongue that some sources compare to a paintbrush. She has a gland at the end of her abdomen called the Dufour’s gland that acts as an ant repellent, but it is also used for liquid food storage and, most importantly, as the base onto which the eggs are laid.

She smears liquid from the Dufour’s gland over the cell’s walls, and it combines with the saliva to make a cellophane-like film that is both waterproof and biodegradable, though it can persist in the soil for several years. She has a gland in her mandibles that produces an antifungal, antibacterial substance that she sprays on the wall as well. She provisions each chamber as she finishes it.

Most ground-nesting bees collect pollen and nectar, form it into a dry “loaf,” and lay an egg on the outside of it. Not the cellophane bee — the provisions she provides are liquid. She suspends her egg from the wall or ceiling of the chamber, closes it off with more cellophane, and then fills the hole with dirt. When it hatches, the larva falls into the liquid and develops there, floating in its sweet food supply, insulated from soil moisture.