Solitary bees are all hymenoptera insects mainly belonging to four families (Colletidae, Andrenidae, Halictidae, and Megachilidae). The most common come from the Colletidae family and are usually called polyester bees or plasterer bees. Their name comes from their habit of covering their underground tunnel walls with a substance resembling cellophane. This family includes at least 46 species in Canada and is the subject of this technical leaflet. Polyester bees are relatively small and measure between 5 and 10 mm in length depending on the species. They are usually quite hairy and can have lighter strips of hair on their abdomen, making them look like small bumblebees.

Polyester bees are among the first insects to come out in the spring. Unlike social insects like the honey bee, polyester bees don’t live in colonies. Each female builds her own nest in the ground made up of several tunnels in which she eventually deposits her eggs. Polyester bees prefer to make their nests in rather dry soil exposed to sunlight. Like most solitary bees, polyester bees are gregarious, so you can find tremendous numbers in a single location, even though they each have their own nest.

For several weeks, females accumulate pollen and nectar from nearby flowers to fill underground cells they have dug. Once that is done, they lay their eggs in each cell before closing it up. The resulting larvae live off their small food reserve and slowly develop throughout the summer. For several species, there is only one emergence period per year. However, there may be a second hatching in the same season. Adults can therefore only be seen a few weeks a year.