We hear a common argument or question about raising hole-nesting bees: In nature, these bees nest in holes in wood, why don’t I just leave them alone? The fact is, the nesting holes we are providing for bees in our bee hotels and bee houses are really different than the nesting holes found in nature.

Solitary hole-nesting north american mason bee

First, imagine a wild place, like a forest or a group of berry bushes. There’s a standing dead tree (also known as a snag), some fallen logs, and some broken or dead branches on trees here and there. A storm broke some berry bushes or deer came by and left openings in the branches. The holes made by grubs are speckled across the snag. 

Natural nesting holes for bees are spread out, snags and cracks in branches can be hundreds of feet apart from each other. Nesting holes are also random in 3D space, maybe one side of the snag still has bark on it and not all branches of the bushes were broken. Holes in the surface of a dead tree are several inches apart from each other.

Standing dead tree in a forest setting, a home for many creatures

Nesting holes in the wild are also spread apart from each other by the natural cycle of time. The snags fall over and become nursery logs and fallen logs are torn apart by bears looking to eat grubs. A new snag develops somewhere nearby, but it’s not exactly in the same spot as the snag before.

The nesting holes that we provide for bees are very different from natural nesting holes. For simplicity, we build one bee house and the nesting holes are close enough together to confuse a nesting female as she approaches. She counts holes and enters a few different ones before finding the one that she’s working on that smells like her. It’s fun to watch her come and go and we can do a better job protecting all of her efforts with the nesting materials in one spot. As humans, we’re creatures of habit and we like to keep the bee house in one constant location (and we like to think that our own home is a permanent fixture of the landscape).

Our man-made bee houses are as close to nature’s perfection as we can manage but they do come with a cost. When hole-nesting bees are in close quarters to each other their population can attract three unwanted consequences: pollen mites, chalkbrood (a fungal spore), and parasitic wasps. When left alone, these threats can completely wipe out an entire population of bees living in man-made nesting sites. Each pest is small but they can move easily between artificially close nesting holes.

The solution to this problem is simple, plan ahead and include the ability toharvest bee cocoons. When you harvest cocoons you separate healthy cocoons from compromised nest chambers and you prevent a population boom of pests. To harvest cocoons safely, nesting materials should be easy to open. At the very least, nesting materials should be inspected and replaced every season.

When you think about it, nature actually does protect hole-nesting bees through the magical work of space and time. Our man-made nesting sites are not the same as wild nesting sites and knowing this the question then becomes if we want to support the bees we are raising or the pests that take the opportunity to take advantage of the bees. That choice is up to you.