Mason Bee House

Asked June 24, 2016, 12:16 AM EDT

A friend gave me a mason bee house several years ago that she'd made from drilling a block of wood. Just this spring I noticed bees had used it for the first time, but I never saw any emerge. In searching for more info, I'm learning that this type of home is very difficult to clean and will be unsuitable for reuse. In the spring, how do I know when to take it down and dispose of it so that the bees cocooned in there now have a chance to emerge but not a chance to get busy reusing it? Is that actually possible, since I expect they will mate right away after the females emerge? Any advice would be greatly appreciated!

Washington County Oregon

2 Responses

Thank you for your concern about the welfare of your mason bees. It’s true that drilled wood blocks should be discarded when used for mason bee housing. The usual recommendation is to do so after 2 or 3 years.

In the meantime, you can look where you might obtain other housing methods, including paper straws sold at some garden centers and bird shops here in the northwest; or stacking trays, some with a clear top so that you can view their activities now and then. Or create your own tubes of paper or of hollow, dead plant stems. One important caution: Don’t use plastic straws.

For now, keep the bee block outdoors in ambient temperature. A good choice is on the east side of the house, where it gets morning sunlight. The bees will be adults in October but won’t emerge until spring, when outdoor temperatures are 50F or so.

After you start using your new housing, you can start cleaning the cocoons in October. Several method exist, among them to wash in water laced with a small amount of bleach, or with coarse sand. You can locate directions for both methods on the web as both text and videos.

One method intended to move the bees from the wood block into new housing is this: In late January, make a hole in the lower edge of cardboard box that can be closed up. Set the occupied wood bee block in the box, close the box and, then set it a distance below the fresh new housing.

Considerable information is available at Also see Raintree Nursery’s info at

Thank you Jean! I really appreciate your thorough answer.