Want a fun activity that benefits native bees and that the entire family can do right in your backyard? Build a bee hotel.

A bee hotel is a place you create for native bees — particularly mason bees and leafcutter bees — to make a nest. "The thing about a mason bee home is that it gets people to understand that there are a lot more bees out there than just honeybees," said Becky Griffin, community and school garden coordinator at the Center for Urban Agriculture and University of Georgia Extension for the Northwest District of Georgia.

"We hear a lot about the decline of honey bees (which are not native to North America), but we need to also be aware that there is a decline in native bee populations due to habitat loss," Griffin said. "Native bees nest in hollow logs, dead trees and in the ground, and when the forest is clean cut, the native bees have fewer and fewer places to nest."

Homeowners can do something to give native bees, which are among nature's most important pollinators, a helping hand by creating special nesting sites. Bee hotels make ideal sites because they are easy to build and will accommodate lots of different species of bees. "Once you start noticing native bees, attracting them and learning about them, you'll just want to sit on your bench in your garden and watch them work," enthused Griffin. "They are amazing creatures!"

Here is a guide, with tips and advice from Griffin, about what types of native bees to expect your bee hotel to attract, how to build a bee hotel, how to measure the success of your bee hotel, and what type of plants to put in your garden to attract and keep native bees in your garden and returning to your bee hotel.

If I build it, who will come?

Even a simple bee hotel will be appreciated by the local bees. Becky Griffin

Bee hotels usually attract what are commonly called mason bees, which get their name from their practice of making compartments of mud in nests they build in hollow reeds or in holes in wood made by wood-boring insects. Orchard bees and leaf cutter bees fall into this category, too. These native bees are called solitary bees because once the female mates, she is on her own. She doesn't have a social structure like a honey bee would have in a hive. She will find a hollow hole with an end to it and she will lay an egg and place some food in it for the larvae and then seal it up with some mud or some leaf debris and go about her business.

When we think of bees, we usually think of honey bees, which have a very complex social structure. They depend on each other; they have a hive and live in a cluster and make honey. But a solitary bee doesn't work as a team with any other bee. They are totally on their own. They will search for nesting material, build nests and gather nectar and pollen all by themselves. They are not part of a social network, and they don’t make honey.

Can I build it?

The first question people who have never seen a bee hotel may ask themselves is whether they have the skills to tackle the project. If you can hammer a nail and drill a hole, then the answer is, "Yes! You can build a bee hotel." It really can be that simple. In fact, it can be simpler if you use bamboo, which is already hollow, for the hotel.

The perfect design

This bee hotel features a number of 'rooms' for bees to leave larvae. Becky Griffin

The first thing you'll have to do is design the hotel. It can be as simple and rustic or as complex and fancy as you want it to be. A simple house could be a 4-by-4 block of wood with holes drilled into it and mounted on a post or even pieces of bamboo that are closed off at one end and tied into a bundle or placed in a tube such as a piece of PVC pipe and hung from a tree. A fancy house could be a square, rectangle or other shape with different sized blocks of wood placed in the frame at pleasing angles. Such a house could even include an art object placed among the wood blocks. While there are no limits to design, there are some basic rules to follow in building the house:

Use only untreated wood.

Make sure the house has a roof to keep rain and other weather elements out of the holes.

The house should be a minimum of three feet off the ground.

To attract as many species of bees as possible, drill holes of varying sizes. Be sure not to drill all the way through the block as the holes must have a stopping point. Drill bits ranging from 2 mm to 10 mm in diameter are ideal. Beginners who might want to keep things really simple and who might have a limited amount of tools could simply use a 5/16 drill bit for all the holes in their first hotel.

For a first hotel, 12-18 holes would be ideal.

There are no hard-and-fast rules on how deep the holes should be — with the caveat that if you use a large piece of wood or create a "grand" framed hotel and the holes are too long, the bee may not enter it. Keeping entry holes no deeper than the length of a standard drill bit is a good rule of thumb.

Remove splinters from the holes. When you drill the holes, take a piece of sandpaper and smooth out the holes. Small splinters may not seem like much to you, but rough edges in the entry holes could be a big deal and even fatal to a native bee, some of which are very tiny. Rough edges can even deter bees from using the hole.

Whatever style of wood you're using for your bee hotel will need to be replaced every two years or so because the bees want new tunnels in which they can lay their eggs.

Resist the urge to paint the hotel. Natural wood is more attractive to the bees.

You can have multiple bee hotels. Just be sure to space them out in your yard and garden so they aren't clustered together.

When and where to place your bee hotel

Native bees nest in the spring. Your bee hotel should be in place in February or, in northern regions, as soon as you can dig a post hole in the spring.

Choose a sunny location where the front of the house will face the sun and that is away from a highly trafficked area. This is important because the bees need the sun to keep them warm, and it's not convenient for bees or beekeepers to have the hotel in a spot where the bees have to fly across a sidewalk or garden path. It's worth pointing out that solitary bees will not sting you except in the unlikely even you were to step on one barefooted or squish one with your fingers.

What to watch for

Sometimes a bee hotel doesn't offer much in the way of dignity for the bees, but it does provide a useful place for bees to reproduce. echoe69 [CC BY-ND 2.0]/Flickr

After you've built the hotel, hopefully the bees will come! Watching for their arrival is a fun part of the project the whole family can enjoy. The females find the hotel in the spring or early summer and enter holes that fit their species size. You can tell what kind of bee has visited the hotel because mason bees will seal holes with mud and leaf cutter bees will seal holes with leaves.

You won't be able to see what happens next, but the eggs will hatch and the larvae will eat the food the female has left behind and then spin a cocoon. A fully formed bee will develop and chew its way through the mud or leaf seal and fly out into your garden world the next spring. It's important that when they do that they find pollen and nectar plants nearby. If not, they will fly off to another garden, and you'll miss the enjoyment of watching the new lives you've helped begin their life cycle. Extension agents can supply you with a good plant list for your region to help ensure the bees stay in your yard. The extension agent can also help you understand what types of bees you can expect to attract in your region.

Another resource to finding the best plants for your region is at your local garden center. Keep in mind that native plants are usually the best choices for home gardens because they are the easiest to grown and get through weather extremes and because native bees have evolved with native plants. Another fun part of the science project is to put a notebook in a sealable baggie and write down the types of bees you see in your garden, the dates when the various holes are sealed and when they have been chewed open. Over time, look for a pattern to the dates.

How to measure success

Once you get the hang of bee hotels and start attracting a lot of bees, maybe you can build a bee hotel as big as this one!. Ong-Mat [public domain]/Flickr

You'll be able to tell if the hotel is being used by observing whether the holes are sealed. You'll also develop an understanding of the bees that are visiting your garden and hotel by the sizes of the holes that are being used. As you add more bee hotels, you may want to increase the number of holes of those sizes. You'll know if you've got the right nectar and pollen plants in your garden by observing whether the bees are visiting them.

On the other hand, if you get to the end of the summer the year after holes were sealed and see that the holes are still mudded over or filled with leaves, then you have a problem with the hotel. You'll have to figure out what that is. For example, a parasitic insect may have noticed the hole is sealed and drilled a small hole through the seal and eaten the larvae or the bee in the cocoon. Or, if you don't notice an entry hole in the seal, a fungus may have killed the bee in one of its stages of growth. Don't spray the hotel to try to prevent this from happening again because you could harm other bees you are trying to protect. Think of it as just one of the hard lessons of nature at work.

Photo credits for inset images of bee houses: Becky Griffin