Woodworking for Wildlife: Observation Hotel for Solitary Bees

By: Frances Owen, JCCB Naturalist

We love talking about solitary bees around here! My fellow naturalist, Kristen Morrow, wrote an amazing and detailed account all about solitary bees last spring on this blog. You won’t want to miss it! Click the following link. Just do it: Spring Awakening: Our Backyard Bees

Bamboo Bee hotel Image by anastaz1a from Flickr

Before we move on with the build, I would like to mention that bee houses and hotels have been gaining popularity as yard ornaments over the last several years. There are around 400 unique species of bees just in Iowa! As the general public has become more curious about these lesser known pollinators, many people have found themselves asking, “How can I help these bees?”

At the very end of Kristen’s blog post (linked above), she offers up a great list of actions YOU can take as a bee steward:

1.) Plant native flowers. The importance of establishing and expanding native habitat cannot be underscored enough. Planting native plants will provide a significant health boost for the web of life generally, not just for the bees. While non-native flowers can be helpful as well, the nectar and pollen resources in native plants are more nutritious for pollinators. Native plants also serve as host plants for other pollinators like butterflies and moths. You might be wondering where you can find native plants. Good news – there are many regional nurseries, including popular nurseries in Iowa, Minnesota, and Wisconsin, that specialize solely in the production and sale of native plants. Check for availability with your favorite local garden center as well.

Start somewhere! If you already have a flower bed started, feel free to add in natives, or replace non-native plants over time. Front and center in this photo is Rattlesnake Master, one of my favorite native prairie plants!

2.) Leave the leaves. Leaf litter is valuable overwintering habitat for some types of bees, including queen bumble bees. If you feel the need to rake leaves, rather than removing leaves entirely, consider redistributing them to other parts of a yard, such as undisturbed corners, as a covering for flowerbeds and gardens, and as mulch around trees.

3.) Provide nesting sites. The majority of bees nest in tunnels in the ground or in cavities in wood and plant stems. To aid the ground-nesting bees, leave some areas of bare ground. To aid cavity-nesting bees, leave flower stems standing throughout the winter and into the spring. Wait until consistent warm temperatures to remove the stems in preparation for the next growing season. You can also use logs intentionally within the yard and garden, as a substrate for cavity-nesters. Use caution when providing artificial “Bee Hotels.” If not properly cared for, some can cause more harm than good. More on that below.

4.) Avoid pesticides. Consider refraining from using lawn and garden chemicals of all kinds. Avoid establishing new pollinator habitat if there is high pesticide use nearby. When purchasing established plants, look at tags and avoid plants that were treated with neonicotinoides, a group of insecticides that are absorbed into plant tissues and can be present in nectar and pollen resources. If you purchased a plant and are worried it was treated, you can remove any flowers during your first year of growth to prevent pollinators from feeding on the nectar and pollen. Most of the pesticide residue should be gone from the plant by the following year and you can leave it be.

5.) Be a citizen scientist! Help track bumble bee populations by submitting photos of bumble bees you observe to Bumble Bee Watch.

I can’t get enough of Bumblebee butts! Click here for more adorable bumblebee photos.

Kristen touched on the dangers of artificial “bee hotels” above, but it really cannot be overstated how important it is to choose an appropriate design, and to continue to take care of it. For the purpose of this blog post, I am going to elaborate on some of the problems with artificial solitary bee structures. Keeping a bee hotel can be a hugely rewarding experience as long as you accept the responsibility of taking care of it. If you decide to purchase a bee hotel instead of building with us, keep the following in mind:

1.) Nesting chambers should be around 6 inches deep for most species. Chambers shorter than that will contain a skewed ratio of male to female offspring. Solitary bees can actually choose to lay male or female eggs, laying female eggs at the back of nesting chambers, and male eggs toward the front. This helps protect female offspring from parasites and predators while possibly sacrificing the less important male offspring (Nature is metal). This also allows the male offspring (which emerge first) to leave the nest without disturbing the other developing bees. In chambers that are too shallow, solitary bees won’t lay as many females, decreasing their reproductive success.

2.) Bee Hotels need to be cleaned out completely every year (or at least every other year) to prevent buildup of disease. Choose designs that are easy to clean, or cheap to replace. Blocks of wood with holes and bamboo canes cannot be easily cleaned out between seasons, and would need to be replaced at least every other year. The woodworking plan in this post makes cleaning fairly simple so that you can continue to use it for many years.

This is a photo from one of our observation solitary bee houses last year. Check out the mud walls dividing all the pollen gathered for the developing bees! Once all the bees are gone, this will need to be cleaned out for the next year.

3.) Opt for smaller hotels with fewer nesting chambers. Large “Luxery Hotels” with hundreds of nesting chambers can attract predators, parasites, and disease. These bees do not typically nest in close quarters with other bees, so this is very unnatural for them.

Large “Luxury Hotel” Image by Manfred Antranias Zimmer from Pixabay

4.) Firmly attach your hotel to a surface in a south facing direction. Free swinging hotels can repeatedly knock larva off their pollen supply, making it difficult for them to feed and develop.

If you’ve made it this far, thank you for staying with us! It is incredibly important to us at Johnson County Conservation that we are not only providing you with fun activities – we also want you to understand where your personal action fits into the larger conservation work we are all striving for.

The following resources come from a public program I taught virtually this winter. I’ve included a full recording of myself building the bee hotel kit, along with a .pdf containing detailed instructions for cutting and assembling the wood. Participants in the class were provided kits, that we pre-cut before the class. I have done my best to supply a plan detailed enough for hobby woodworkers to successfully attempt the build. If you have any questions about the build process, or just want to show off your rad bee hotel, comment below!

Details for hanging, applying a protective finish, and for long term care of your bee hotel are also included in the plan. Happy building y’all!

Click here for a complete .pdf of the build.

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