Pat Mosley's Unofficial Guide to Sizing Bee Hotels
So, you’ve gathered up all your materials, you’ve picked out your cutesy design features, and you’re all set to build your first bee hotel. All of the sudden, with drill in hand and ready to go, you realize you’ve forgotten to plan a very important part of your design. What size holes do we make?
After ‘what amount of long-term care is involved?’ this is probably the second-most common question I get about bee hotels. And much like the former question, it’s answer can be ambiguous depending on who you speak to, how the bees in your area are behaving, and really, how much you’re trying to engage in this kind of work.
In North America alone, there are more than four thousand different native bee species. That’s four thousand types of bees who aren’t the honeybees most folks associate with beekeeping! This means there can be upwards of four thousand different preferences for nest design. And even that number presupposes no variation across species, which anyone who has spent any time with more than one human or animal can tell you is a big assumption to make.
So what does this mean for would-be bee hoteliers?
Well, we have a couple places we can go for answers. In my own experience, I’ve heard from furniture makers and woodworkers that they associate some very specific size dimensions with the holes different bee species bore into wood (often being the material for their products).
Among wild beekeepers I’ve talked with, the answers are a little more varied. Some wild beekeepers have observed their neighbor bees adjusting the sizes of slightly smaller holes, while ignoring larger holes all together. Depending on the kind of ecological advocacy happening near you, you may find research into this subject has already been performed locally. In my own survey of some of the research out there*, wild bee nesting hole preferences tend to cover a range of sizes, rather than very specific numbers only.
Importantly, I think we need to recognize our objective alien nature to the life of bees. As humans, we don’t know offhand how they will react to resource scarcity, climate change, or other factors. At best we can base our wisdom in observation which may at times only be relevant to certain micro-ecosystems. In other words, go with your gut in what sources to trust regarding nesting hole design, but be prepared to adapt the models you build if it doesn’t work out.
All that said, there are a few figures out there that I will provide here as guidelines for a handful of the wild bee types likely to be encountered in North America.
For bumblebees and carpenter bees, drill holes between 1/2 and 5/8ths of an inch in diameter.
For mason bees, drill holes between 5/16ths and 3/8ths of an inch in diameter.
For leafcutter bees, drill holes between 5/32nds and 1/4th of an inch in diameter.
Depth of the nesting holes also matters. As a general rule of thumb remember this principle of threes:
For holes 1/3” or smaller in diameter, drill nesting holes to a depth of 3”
For holes greater than 1/3” in diameter, drill nesting holes to a depth of 6”
Read More: Long-Term Management for Wild Bee Hotels
Other helpful tips:
Carpenter bees have the perfect jaws for making their own tunnels, try leaving them some soft wood to burrow into on their own.
Mason and leafcutter bees both love keeping their nests lined up in neat rows, and don’t mind re-using nests beetles have previously used.
For folks with fruit orchards (or those in the Southeastern Appalachians with redbud trees nearby), you may try attracting the blue orchard bee, a type of mason bee some farmers are attempting to breed as a replacement for honeybees now. Use cedar construction materials when possible, and be sure to place your hotel where it has access to mud for nest-building. I’ve heard that these bees also prefer a reed design.
If you get beetles instead of bees, try to identify them and learn more about their role in your ecosystem. Perhaps you need beetles more than bees!
In the end, just be willing to experiment. When we’re designing something for wildlife in our neighborhood, we’re not just following a static blueprint for industrial-like design. We’re entering into dialogue with the wild animals we share this space with. Watch how they interact with your creation, take notes, try something else, take more notes, and share this feedback with the rest of us!
As I’ve said before, this area of apiculture is still being charted. There are few solid, universal answers, but plenty of grey areas already to explore. This frontier offers so much for so many of us to get out and work with, and I hope you’ll join me in learning all we can about how to better live with the wildlife in our neighborhoods.
*The University of Nebraska—Lincoln Extension, Institute of Agriculture & Natural Resources has in my opinion one of the most succinct and visual guides to bee hotel nesting hole sizes that I’ve seen on the web. You can check out their free publication here.
Patreon subscriber? I’d love to discuss these topics more in depth, including your own experiences with wild bees and insect hotel building. If you haven’t yet joined the team, for as low as $10/month, you can join the discussion on blog and video posts like this one. Head over and check it out!
Pat Mosley (NC LMBT #16882) is a licensed massage and bodywork therapist in the Winston-Salem area. His work is rooted in compassionate touch, permaculture, and deep ecology with the resilience of all Earth's children in mind. Connect with him via email to firstname.lastname@example.org