What Kind of Bees Go Under Siding? Identification Guide

As a homeowner you may have noticed bees flying in and out of small holes they’ve drilled into the siding of your house. This activity is usually a sign that bees have set up a nest behind the siding. But what kind of bees are these home-invading insects?

There are a few main types of bees that commonly construct nests under siding. This article will identify the culprits and explain what attracts them so you can try to deter their nest building.

Carpenter Bees

The most likely suspects nesting under siding are carpenter bees There are two species common across the United States – the eastern carpenter bee and the western carpenter bee

Some identifying features of carpenter bees:

• Large, robust, black and yellow or black and white striped bodies.

• Size ranges from 1/2 inch to nearly 1 inch long.

• Males have a yellow face while females have a black face.

• No hair on the abdomen unlike bumble bees. Smooth, shiny surface.

Carpenter bees drill perfectly round holes about 1/2 inch wide into untreated wood surfaces. The holes lead to tunnels and chambers excavated in the wood where they rear larvae.

Carpenter bees prefer to nest in warped, weathered or unpainted wood. They are strongly attracted to bare wood siding, eaves, trim, deck railings, outdoor furniture and other structures.

Mason Bees

There are around 400 species of mason bees in the genus Osmia native to North America. These metallic blue-black bees use mud or chewed up leaves to build nests in existing cavities.

Mason bees are smaller than carpenter bees, ranging from 1/4 to 5/8 inch long. They will use holes already present in siding rather than drilling new nest entrances. Abandoned beetle holes, gaps between boards, and crevices are ideal mason bee nest sites.

Leafcutter Bees

Over 130 leafcutter bee species live in the U.S. and Canada. As their name suggests, they cut pieces of leaves to build cocoons for their larvae inside holes in dead wood.

Leafcutter bees are about the size of honeybees with black, gray or brown bodies and light yellow or white hair. They nest in narrow tunnels and cavities in wood siding, fence posts, and dead trees.

Mining Bees

There are around 100 types of mining bees in the genus Andrena. These small, fuzzy bees dig burrows in soil but will also nest in holes in wood, rock crevices, or hollow plant stems.

Mining bees have black bodies with light hair bands across their abdomens. Under siding, they prefer very narrow tunnel diameters just wide enough for a single female bee.

Why Bees Nest Under Siding

There are a few reasons bees so often choose the space behind exterior siding for their nests:

• Wood siding provides an existing cavity without the need to dig soil tunnels.

• The narrow gap between siding boards offers shelter from rain, wind and predators.

• South or west-facing siding warms up in the sun, helping incubate larvae.

• Paint or stains often degrade over time, exposing attractive bare wood.

• Siding shelters nests from lawn mowers and human activity.

• Nearby flower gardens provide ample nectar and pollen.

Once an initial pioneer bee colonizes the area, pheromone secretions can attract secondary nesters. Soon you may have dozens of bees busily entering and exiting the holes.

Preventing Bees Under Siding

To deter bees from moving in under siding:

• Seal any holes, cracks or gaps in siding with caulk. Check areas around pipes or wires.

• Keep wood surfaces painted or stained regularly to cover attractive bare wood.

• Install nest boxes for bees away from the house to redirect them from siding.

• Attach window screening or hardware cloth over problem areas to block entry.

• Use bee-repelling plants like mint, lavender, and marigolds around the home’s perimeter.

• Inspect and fill small holes as soon as you notice them to prevent expansion.

• Consider replacing wood siding with vinyl, metal, or composite boards less prone to damage.

Keeping your siding in good repair is key to denying bees access. But if they still get established, it’s best to call a professional exterminator to safely remove the nests. Be patient, as bees under siding are a common nuisance. With vigilance, you can keep those buzzing insects from moving in next door.