How to Build Simple Nest Boxes with Native Plants for Cavity-Nesting Bees

Mason Bee, Osmia sp.

Mason Bee, Osmia sp.

I had great success last season with cavity-nesting bees using the hollow plant stems I collected and placed in various parts of yard. I am reminded as I wait for spring that many of the plant stems sticking up through the snow may already be filled with broods of larvae ready to emerge this spring. Another reason to not clean-up your garden in the fall because the leaves, branches, hollow stems, decaying wood and debris provide important overwintering sites for wildlife.

Yellow-Faced Bee Hylaeus sp.

Yellow-Faced Bee
Hylaeus sp.

Native bees are abundant in urban and suburban landscapes and approximately 30% nest in cavities. Cavities include plant stems – some bees chew the pithy wood from the center of stems, others use preexisting holes in wood, most often in standing dead trees. Common cavity nesting bees are small carpenter bees (Ceratina spp.), mason bees (Osmia spp.), leafcutter bees (Megachile spp.) and yellow-faced bees (Hylaeus spp.).

 

Spotted Joe Pye Weed

Spotted Joe Pye Weed

There are many native perennial plants with hollow stems that can be collected and bundled to create nesting boxes. Bee boards are often constructed for mason bees by drilling long dead end holes in untreated wood boards, usually in 4″ or 6″ square boards. These boards require cleaning every two years with a bleach solution to eradicate any pathogens or disease-causing organisms. I have found hollow plant stems much easier to maintain because they can be easily removed and replaced every two years, and they are also abundant in my yard. Lay the old stems on the ground if empty and keep the others in a safe place until the larvae have emerged.

Bee Nest Box

This box is constructed of plywood with a piece of aluminum on the roof.

I purchase untreated 1×8″ or 1×10″ boards from my local lumber store where they sell remnant pieces for less than $2. Create an open-ended box, rectangular or square and hang in a sunny location on a fence. Put a back on the box if you plan to hang it where there is access to the back so woodpeckers don’t disturb the stems.  The box should be at least 6″ deep; cut hollow stems to the length of the box and fill full.

Pale Indian Plantain

Pale Indian Plantain

Hollow-stemmed native perennials include cup plant (Silphium perfoliatum), joe pye weeds (Eupatorium spp.), pale Indian plantain (Arnoglossum atriplicifolium) and larger sunflowers (Helianthus spp.). While cutting down your perennial stems this spring, take a look at the plants in your landscape to determine which ones you could use for bee nests.

Small Carpenter Bee Ceratina sp.

Small Carpenter Bee
Ceratina sp.

For shrub species, small carpenter bees like stems with pithy centers that they chew out to create a cavity. Elderberries, Sambucus spp. are ideal stems to collect. In the midwest, both the red elderberry, Sambucus racemosa and the Canada elderberry, Sambucus canadensis are abundant.

Grass-carrying wasps, Isodontia spp. also use hollow stems as nesting sites. These wasps are solitary and do not sting. Females fill the stems with prey (crickets and katydids), lay their eggs then seal the cavity with pieces of grass.
Grass-Carrying Wasp NestThere are many creative examples of solitary bee nests, some people build beautiful ‘bee hotels’ with multiple layers of stacked stems, wood and other crevices. What natives in your area have hollow stems that can be used for bee nests?

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Comments

  1. says

    Heather this is wonderful! I am going to make some of these. I have an old bee house from Gardner’s Supply and I think I’m doing more harm than good! I like the idea of the stems as I can swap them out easily. I’ve passed this post along. Also, I just read on Solitary Bee that if I do drill holes in logs that I should line them with paper to swap out? I hope to learn more about it.

      • says

        Hi, I am interested in doing this , this year, but have a few questions. I left a lot of my perenniells over wintering. When can I cut them up, not to disturb any larva that might be there? When do the bees start using these tunnels? Or to be put another way , when should the bee house be up to be most useful? When do you decide it is safe to throw away old stems and put new ones in. I guess I am wondering about your timetable for all this. thanks

  2. says

    Nice article Heather. I like your how-to with pic example of the bee house with aluminum roof. Also nice to hear of the elderberry twig use. We have blue elderberry here in the west and I was lucky to find some cuttings left behind by a park service. Openning Soon: Bumblebee Blue Elderberry Resort.
    Tony McGuigan recently posted..20130218 Food Ridge West Hugelkulture

  3. says

    Very informative article! I posted it on my FB page and have gotten a lot of good feedback. I often find the pith removed from my hydrangea stems as well. I also recommend using Phragmites and Teasel stems, since the bees really love them AND you’ll be removing invasives at the same time! Bamboo is good also, but very difficult to open up in the fall.

    I sell the eastern species of the Orchard Mason Bee (any state east of the Rocky Mountains) if you ever need some. As I’m sure you know, it’s important to introduce the species that is native to your area, and O. lignaria lignaria is much better adapted to heat and humidity.

    Thanks for spreading the word about our native pollinators!

    Denise Shreeve @ Our Native Bees

  4. says

    Great info Heather! I am looking into this for this year. I was wondering if you know if you HAVE to take out the cocoons or can you just let nature takes its course? Thanks for the post!

      • says

        Hi Heather,
        Opening the tubes isn’t necessary, but it does result in healthier bees, since anything that doesn’t look like a healthy bee cocoon (i.e. cells filled with pollen mites) can be discarded. The bees have to chew through the mud divider walls, and walk through each of those cells to emerge, so eliminating things like mites and predators that might be lurking, is doing them a big favor.

        However, if you don’t want to open them before the nesting begins in early spring, it’s very important that you open the tubes about 2 – 3 weeks into the spring season. The female bees are always laid at the innermost ends of the tubes, and many healthy girls get trapped back there by dead bees in front of them or any number of blockages! Remember, they don’t sting, and you’ll be saving lots of potential Moms. ;-)

Trackbacks

  1. [...] 23. How to Build Simple Nest Boxes with Native Plants for Cavity Nesting Bees, by Heather Holm. “Many native bees are cavity nesters, including the stems of your native plants. So don’t be too eager to clean up in the fall because you’ll be throwing away many of these beneficial native bees.” [...]

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