Earth-friendly solutions for organic gardeners.

Tag Archives: building a mason bee house

Mason Bee Mystery

Mason Bee Mystery

Here’s an update on my mason bee mystery. If you read my first post about building a mason bee box, you know that my mason bee box has about a dozen nests that were clearly built by mason bees. Those nests are capped off with mud, and were all completed within mason bee season, which typically runs from March through May.

Mason Bee BoxHowever, in the middle of July, several new nests appeared. These nests are clearly not the nests of Mason bees. These nests are bright green and bright red. Here’s a photo.  So the question remains…what type of insect has decided to nest in my mason bee house?

I have two contradictory feelings about these nests. I’m concerned, because these nests may hatch insects that are predators for mason bees. I would be very distressed if I lost all of my little pollinating friends to insects that are higher on the food chain.  On the other hand, predators have their place in nature, and therefore should have a place in my garden.

My first course of action was to do some research. I contacted a few different Websites that specialize in mason bees. I even posted a query to Facebook. And for the most part, I didn’t get any response. The one exception is If you don’t want to build your own mason bee box, Mason Bee Central is a great resource for supplies of all kinds.

I received two emails from my inquiry to Mason Bee Central from Gord. And while Gord wasn’t able to identify the interlopers, he did give me some good advice. He suggested that I take the nesting blocks out of the garden after mason bee season is over. By placing the blocks in my garage or garden shed, I can guarantee that other insects won’t use the blocks for their own purposes.

A Different Kind of Bee

Leafcutter bee nests
Photo courtesy Christine Farmer,

But this still left me with a mystery. What in heaven’s name was nesting in my Mason Bee box? Honestly, I’m still not sure. But while surfing gardening sites the other day, I stumbled across a potential answer. Here’s a photo I found on, it shows very clearly that the nests of leafcutter bees are sealed with…you guessed it…leaves. The leaves could account for the different colors of these nests.

Leafcutter bees are solitary bees, just like mason bees. And they build nests, just like mason bees. However, leafcutter bees are active through late summer. Given that I noticed these nests in July, I’m betting that leafcutter bees are quietly maturing in those brightly colored nests.

I will keep an eye on the bee box. I’m hoping that I can observe the bees when these nests begin to hatch. Hopefully, I can confirm that this bee box is home to both mason bees and leafcutter bees. If you have experience with mason bees or leafcutter bees please leave a comment below. I’m eager to learn anything you can share!


Mason Bees in My Garden

Mason Bees in My Garden

By now, if you’re a gardener, you’ve read about those industrious little orchard mason bees (Osmia lignaria). Native, wild bees—like the mason bee—don’t live in hives and they don’t make honey. They pretty much do only one thing, and they do it exceptionally well. They pollinate fruiting trees and plants. In fact, according to Crown… Continue Reading