Ways to help bees find places to live

We hear a lot about bees (and other pollinators) and the plants we can plant to help them. And it is true, to live and thrive pollinators need food, and that food usually comes from plants. However, we often forget that they need something else to thrive: a place to live! In fact, most bees do not live in colonies like honeybees do, and are solitary. These bees are indeed the vast majority of bees, and, only in Maryland, we have about 400 different species of them, going from tiny to very large. Each of these wild bee species has different nesting requirements, and many of them will readily nest close to our houses, if they find the right conditions. Here are some pointers on how to create those conditions to not only attract bees with flowers, but also help them live close to us.

How do wild bees live?

Wild bees usually lay eggs only at certain times of the year, and usually at only one point throughout the growing season (for example, only in the spring, the summer or the fall).

Wild bees lay eggs in their nests and leave food to them. When the larvae hatch they find the food and can finish their development in the absence of the mother. Photo: USDA ARS.

Whenever they are ready to lay eggs, bee mothers start looking for a place to nest, and it is only during this time that they will be building their nests. Once the eggs laid, the mother leaves and those eggs stay in the nest along with some food (usually pollen mixed with some nectar). After hatching, the larvae go on and eats the food the mother left for them, and continue feeding and growing until they are ready to leave the nest as adults, usually the following year. This means that for most bees, there is no or very little maternal care of the offspring, and that most of the time spent in a bee’s life is as a larva, growing and getting ready for the “outside” world.

Where do wild bees live and how can I help them nest?

Wild bees have a variety of nesting preferences, with some nesting in the ground, where they dig galleries, others digging holes in the wood, others using already-existing cavities, and others parasitizing other bees’ nests. Understanding this is important, because depending on the resources we provide for nesting, different species will be attracted to our gardens.

Keep some ground undisturbed - Ground-nesting bees

The green sweat bees are very common in Maryland and can be often seen digging on bare ground and visiting flowers. Photo: K. Achtmeyer (CC0). [https://www.inaturalist.org/observations/208719766]

If you would like to support these bees in your garden, you can make sure to leave some soil undisturbed or bare. If you do this, you will realize that many bees will be attracted to that section, and if you pay attention, you’ll realize that many are actually coming in and out of the ground! These are your ground-nesting bees! In Maryland, some ground-nesting bees that you may have seen visiting flower are the small and shiny green sweat bees.

Leave some wood in your yard - Carpenter bees

The large carpenter bees nest in shallow galleries they excavate in soft wood. Photo: Missouri Department of Conservation.

In our region, these bees are represented by the very large shiny carpenter bees of genus Xylocopa. These bees have strong mandibles that they use to excavate soft wood, to build their nests in it. If you would like to attract these bees to your garden, make sure to leave relatively large branches and logs available for them to nest in. For this, you can turn a corner of your yard a bit wilder, and at the same time, leaving those branches in there will also allow other beneficial organisms to establish in your garden.

Cavity-nesting bees

A local bee attracted to bee hotels is the flat-tailed leaf cutter Megachile mendica. Photo: C. Martin (CC0) [https://www.inaturalist.org/observations/232832400]

These bees do not create the cavities, but rather use those that already exist. This is the group of bees that is attracted to those cute bee hotels one can build or buy. A natural option for supporting these bees is not cutting down to the ground the hollow stems of some plants at the end of the season. Many bees nest within these stems, and will die if they are chopped-off during the winter. Species in this group of bees nest in the spring, summer or fall.

There are a multitude of types of bee hotels. Independently of the type of bee hotel you want to use, something important is to make sure that you keep the cavities clean for the bees to develop in healthy conditions. Failing to do so may actually harm the bees we’re trying to support, because they may still be attracted to the nesting site we’re providing, but may eventually become sick and die because the place was unhealthy.