How to Get Rid of Carpenter Bees | Pest Control Insider

In late spring, you may notice large, bee-like insects hovering around your porch rafters, deck railing, or wooden fence. The males often dart aggressively at anything that comes near. Meanwhile, the females are quietly drilling half-inch holes into your home’s wood.

Those are carpenter bees, and they can cause real structural damage if left unchecked season after season.

Carpenter Bee vs. Bumble Bee: How to Tell the Difference

Before doing anything, confirm you’re dealing with carpenter bees and not bumble bees. They look similar but behave very differently.

Carpenter bee:

Black and yellow, about 1 inch long
Abdomen is smooth and shiny (not fuzzy)
Males have a yellow face; females are all black on the face
Hovers and darts near wood structures
Does not live in colonies — nests alone

Bumble bee:

Similar size and coloring, but the abdomen is fuzzy with yellow or orange bands
Lives in colonies underground or in dense ground vegetation
Less likely to be found hovering repeatedly near wood structures

If you are seeing perfectly round holes bored into wood, you have carpenter bees. Bumble bees do not drill wood.

Why Carpenter Bees Are a Problem

A single pair of carpenter bees may not seem alarming. The problem is that they return to the same wood year after year, and each generation extends and deepens the existing tunnels.

Structural damage: Tunnels run six to twelve inches deep after the first season, and can extend two feet or more in subsequent years as offspring return. Multiple tunnels in the same beam weaken structural integrity over time.
Woodpecker damage: Woodpeckers hear larvae inside the wood and aggressively peck it open to feed on them. This secondary damage is often worse than the bees themselves.
Moisture intrusion: Unsealed holes allow water inside, which leads to rot.

When Carpenter Bees Are Active

Carpenter bees overwinter as adults inside their galleries. In spring (typically March through May, depending on your region), they emerge to mate. Females then drill new galleries or return to expand existing ones.

June is the ideal time to treat. By now, the females have laid eggs and the tunnels are sealed with a pollen plug. Treating in early summer kills the larvae inside before they mature. Treating in late fall targets adults that have returned to overwinter.

How to Get Rid of Carpenter Bees: Step-by-Step

Step 1: Treat Active Galleries With Insecticide Dust

Insecticide dust is the most effective treatment for active carpenter bee galleries because it reaches deep into the tunnel where sprays cannot penetrate.

Products to use:

Delta Dust (deltamethrin) — Waterproof, long-lasting, available to homeowners
Drione Dust (pyrethrins + silica gel) — Fast-acting, effective
CY-Kick Aerosol — Aerosol with a straw applicator, useful for tight angles

How to apply:

Locate all holes — they are perfectly round, about 1/2 inch in diameter, usually on the underside of wood
Use a bulb duster or the aerosol’s straw to inject dust or spray directly into the hole
Do not plug the hole immediately — you want foraging bees to walk through the treated area and carry the insecticide inside the gallery
Leave the holes open for 24 to 48 hours after treatment

Safety note: Wear gloves and a dust mask when handling insecticide dusts. Treat at dusk when bee activity is lowest.

Step 2: Seal the Holes With Caulk or Wood Putty

After 48 hours, seal every hole with an exterior-grade caulk, wood putty, or a small wooden dowel and wood glue.

Sealing traps any remaining larvae inside and prevents new bees from entering
Use a color-matched caulk or putty to blend with the wood
Sand smooth and apply paint or stain over sealed holes

Do not skip this step. Unsealed holes attract new females the following spring — they strongly prefer to reuse existing galleries rather than drill new ones.

Step 3: Apply a Residual Surface Spray

Spray an insecticide with residual activity on all exposed wood surfaces where carpenter bees land and investigate. Focus on:

Fascia boards, eaves, and soffits
Deck rails and posts
Fence boards
Porch ceilings and joists

Good products for surface treatment:

Cyzmic CS (lambda-cyhalothrin) — Long residual, outdoor labeled
Permethrin SFR — Broad-spectrum, economical for large surfaces
Suspend SC (deltamethrin) — Low odor, good for wood surfaces

Apply with a pump sprayer in late afternoon or early evening. Reapply every 4 to 6 weeks during active season or after heavy rain.

Natural Methods That Have Limited Effectiveness

You may read about essential oil sprays (citrus, tea tree, lavender) or almond oil applied to holes. These can deter bees briefly but do not kill larvae or provide lasting repellency. Citrus peels hung near galleries have the same issue — short-lived deterrence, no kill.

The only non-chemical method with real teeth is exclusion: paint or stain all exposed wood so bees have nowhere unprotected to drill. See the prevention section below.

Carpenter Bee Traps

Carpenter bee traps work by mimicking a pre-drilled gallery. The bee enters through a hole at the top, falls into a jar below, and cannot escape. They are sold under brand names like “Catchmaster” and “BuzzBee.”

When traps work: They are effective as a supplemental tool during peak activity (April through June) and can catch significant numbers when placed near active areas.

When they fall short: Traps do not treat existing galleries or kill larvae. Combine traps with insecticide treatment for best results.

Prevention: Stop Carpenter Bees Before They Start

Prevention is far cheaper than treatment over the long term.

Paint or stain all exposed wood. Carpenter bees strongly prefer bare, unfinished wood. Painted or stained surfaces are not impervious, but bees will almost always choose bare wood if it is available. Maintain paint and stain on all exterior wood surfaces — check and recoat every few years.

Replace soft woods with hardwoods or composite materials. Carpenter bees prefer cedar, pine, and redwood. Hardwoods like oak or pressure-treated lumber are much less attractive. Composite decking, vinyl trim, and fiber cement siding offer no viable drilling surface at all.

Fill cracks and voids. Any pre-existing crack or gap in wood is an invitation. Caulk these before carpenter bee season begins in spring.

Inspect each fall. Walk your exterior in October and seal any new holes you find. This removes the overwintering sites that bring bees back in the same spots every year.

Do Carpenter Bees Sting?

The males — which are the ones you see hovering and dive-bombing near the nest — cannot sting. They have no stinger. Their defensive behavior is entirely display.

Females can sting but are docile and rarely do so unless handled directly. Carpenter bees are not aggressive in the way yellowjackets or hornets are.

That said, treat any bee with respect. If you are allergic to bee stings, use extra caution or hire a professional.

When to Call a Professional

Most carpenter bee problems are manageable as a DIY project. Consider hiring a professional if:

You have extensive galleries across multiple structural members
You are seeing significant woodpecker damage, which suggests a heavy infestation
The affected wood is high up (second-story soffits, high roof peaks) and requires scaffolding or extension ladders
Repeated DIY treatments have not reduced activity

A pest control professional will typically apply a higher-concentration residual dust, treat all accessible galleries, and may offer a warranty on re-treatment. Expect to pay $150–$400 depending on the extent of the problem and your region.

Summary

Step	Timing	What to Use
Treat active galleries	June or fall	Insecticide dust (Delta Dust, Drione)
Seal holes	48 hours after treatment	Exterior caulk or wood putty
Surface spray	Spring through fall	Permethrin SFR or Cyzmic CS
Prevention	Before spring	Paint/stain all bare wood

Carpenter bees are a manageable problem when you treat early and follow up with proper sealing and prevention. The biggest mistake homeowners make is sealing holes without treating first — the larvae mature the following year and emerge into new bees, starting the cycle over again.