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Building a Bee Condo

There is a growing interest in helping our native bees by planting pollinator plants, using less pesticides, and providing bee condos. Bee condos, also called bee houses or bee hotels, provide tiny spaces for bees in which to lay their eggs. These condos can be store-bought or homemade using reeds, paper straws, or drilled wood.

Who “Bee-longs” in a Bee Condo?

While bee condos provide nesting sites for only a small number of native bee species, they are a fun way to learn about these fascinating insects. Non-stinging Mason bees of the family Osmia are an example of a bee that will use bee condos. These above ground nesters use the hollow stems of reeds and other dead plants, or holes in wood made by wood-boring insects. Small solitary wasp species also use hollow stems. These harmless insects will feed on small pest insects.

Bee condos are the bee鈥檚 permanent home for 11 months of its life as it develops from an egg, through the larval and dormant pupal stages, before it finally emerges as an adult. Thus, once you have made a bee house, you should commit to managing it properly.

Note: Bee condos are not for every species. European honey bees and native bumblebees will not use the kind of bee houses described here. Honey bees live socially in large hives, and bumblebees live in smaller communities underground. Most solitary bees also don鈥檛 use bee houses as they make individual nest cells for their larvae in small tunnels or holes in the ground.

Building the Condo

Size

Smaller is better. In the wild, Mason bees rarely live in large numbers in close proximity to each other, so smaller condos spread around a property is better than one large condo. Also, large bee condos could invite parasites and diseases if not carefully managed.

Designs

There are two basic designs, the reed-filled can and the drilled wood block. You can combine the two designs with small pieces of drilled wood within a larger structure with reeds.

Reeds in a Can

• Collect hollow stems from plants such as grasses, reeds, tall flowers, and shrubs (e.g., Phragmites, raspberries, teasels, and elderberry). Alternatively, you can purchase bundles of narrow bamboo canes (1 to 10 mm diameter) at garden centres or use paper straws or rolled up paper. Do not use plastic or glass tubes.
  • Note: If using non-native plants such as Phragmites or teasel, ensure you cut off the seed heads and put them in a garbage bag before using the stems. This will prevent spreading the seeds.
• Clean out an empty tin can (e.g., soup/bean can) and smooth down any sharp edges along the open rim. Do not remove the bottom of the can.
• With a sharp utility knife, cleanly cut each reed to fit the can (usually slightly shorter than the can).
• The reeds should be free of splinters or cracks that could harm the bees. Ensure the stems are completely hollow and not blocked by pith (the soft center inside the stem).
• A range in the diameter of the nesting tubes will attract a range of different species.

Drilled Wood Block

• Cleanly cut blocks of wood (e.g., untreated 4′ x 4′ cedar posts) or sections of small tree trunks, 20-30 cm (8-12 inches) long.
• Mark the location of the holes in one end of the wood. They can be random or in straight rows.
• Drill holes using a variety of drill bits for a range of diameters, 1/4 inch (6 mm) or smaller. Drill the holes 3 to 5 inches (8-12 cm) deep, or as deep as possible. Smooth out any ragged edges.
• Bees prefer dark coloured homes, so consider charring the front of your bee condo lightly with a torch. Or, leave the block of wood outside for a season to age, and then drill the holes into it. Do not use paint or stain as the chemicals may be harmful to the insects.

Installing the Condo

• In May, mount the bee condo outside on a post or attach the post to the side of a building. The drilled holes/tunnels should be horizontal or parallel to the ground.
• Place in a warm location with southern or southeastern exposure and protected from rain. A good place could be under the eaves of a garage or shed.
• Position the hotel at least 1 metre above ground. Higher is better. Do not hide the entrance with vegetation.
• Mount securely so it does not sway in the wind.
• Replace drilled wood blocks or reed cans every year or two, or as they get moldy or infested with parasites.

Bee Activity

During spring and summer, the mother bee visits many flowers to gather pollen and nectar for her nests. Many trips are needed to complete a pollen/nectar provision mass. She then lays her tiny egg on top of the mass and seals the cell with mud. The process continues until she has filled the entire cavity/tube and seals the entrance.

After the egg hatches, the larva develops rapidly by eating the nutritious mixture of pollen and nectar. The larva then spins a cocoon around itself and enters the pupal stage. The adult matures either in the fall or winter, hibernating inside the cocoon until it is ready to emerge the following spring or summer.

Protecting Bee Condos

Winter Protection

The hibernating young bees need to be protected from wet, winter weather. In the fall, you can remove the bee houses from their location and keep them in a cold, dry place. An unheated shed, porch, or carport is ideal. Do not store in a warm place. Wet conditions, not cold, are their enemy. Move the bee condo outdoors in late March before they emerge.

If your bee condo has a good overhanging roof and is completely rainproof you can leave it outside.

It is best to have two condos:

• Leave one condo out May to October. In November, bring it in to an unheated shed over winter. Put the condo in a dark plastic container/tub (e.g., Tupperware) with a lid and a hole(s) in the side. In spring, put the container and stored condo outside. The adult bees will go out the side hole, attracted by light, and head straight to your garden flowers. After the insects have left, remove and discard the first condo and clean the tub/container with water and diluted bleach solution.
• Have a second bee condo to hang up in May so when the adults are ready to lay eggs, they have a new place in your yard to make a nest. In November, bring in this second condo and place it in the clean tub for over-wintering.

Bird Protection

If you notice woodpeckers or other birds attacking the tubes looking for bee larvae, fix a piece of chicken wire across the front of the bee house, keeping it a couple of centimetres away from the front of the holes.

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