While 70% of our solitary native bees are ground nesting, the other 30% are cavity nesting. They make their winter homes in old wood such as plant stems, or cracks, crevices or beetle tunnels in logs. Like ground nesting bees, cavity nesters build individual cells for their eggs and supply them with the necessary pollen balls. Once provisioned, each cell is sealed off with a partition constructed from mud. Then other cells are added until the cavity is full, and the end is capped with mud.
When laying eggs, the female bee makes use of an interesting super-power that some human parents might envy: She is able to decide whether to lay a male or a female egg. Usually, she will choose to lay female eggs first, and will place the males closest to the entrance. That way, when the new bees begin to emerge in the spring, any predators that are lurking will seize upon the males first-- hopefully allowing the females to escape unscathed! (Sorry, guys.)
How can you help these industrious insects to survive the winter? First, leave your pollinator garden clean-up for the spring. Allowing plant stems to stand through the winter provides important overwintering sites for cavity nesters. A brush pile or pile of logs in an inconspicuous spot also offers plenty of shelter. As you look out at the cold, snowy landscape, you can bask in the warm glow of the knowledge that you’ve provided snug winter homes for many pollinator friends!
Author: Lisa Schneider
Photo credit: Habitat Network
Snetsinger Butterfly Garden Knowledge Series