Here in Montana, we generally see our first Orchard Mason Bees of the season by mid-April. Resembling a large fly, the males of these bluish-green native bees emerge first, waiting patiently for the females to emerge in a week or so to mate.
After mating, the females’ focus quickly turns to finding a suitable nesting site. They create nests in long, thin tubes – like hollow plant stems, natural cavities in wood, or the artificial hotels some bee lovers provide them.
Having identified a prime spot, a female will start building her nest at the very end of the tube. Collecting mud with her mandibles, she’ll line the back of her nest chamber with the muck she gathered, creating a cell that she’ll carefully provision with pollen. She’ll then lay a single egg and seal off the cell with a mud partition that doubles as the beginning of her next pod.
Having chosen a nesting tunnel deep enough to lay 5 or 6 individual cells back to back, she’ll seal the end of the cavity with a heavy cap of mud.
In the months ahead, her developing young will eat Mom’s pollen stash, develop into adult bees, and hibernate for the winter to emerge next spring.
But hold on! If males emerge out of this long tube of egg cells first, what happens if a cell with a female bee is blocking the way out?
Relax. It turns out that Mom has that covered. When laying each egg, she already had a plan in place. Fertilized eggs (which create females) are laid toward the back of her tubular nest, while unfertilized eggs (creating males) are laid at the front.
Lesson learned. Never underestimate Mom’s ingenuity.