🧰 Tools & Materials
Delta DustHand duster/bellowsSteel woolWood putty or caulkPaint
📋 Step-by-Step
1
Treat existing holes at night
Carpenter bees are less active at night. Using a hand duster, inject Delta Dust (deltamethrin dust) into each existing hole. The dust disperses throughout the tunnel, contacting larvae inside and any adult returning to the nest.
2
Wait 1-2 weeks before plugging
Bees must contact the dust and die before plugging. If you plug immediately, living bees chew through the plug (or chew a new hole nearby) and the treatment is wasted. Wait 7-14 days after treatment before plugging.
3
Plug holes with steel wool then wood putty
Pack steel wool into each hole as a physical barrier, then fill flush with wood putty or exterior caulk. Paint over the filled area.
4
Apply finish paint to all bare wood
Carpenter bees strongly prefer unpainted, bare wood. Painting all exposed wood surfaces — including the undersides of boards — dramatically reduces new attacks.
5
Apply liquid permethrin to beam undersides as preventive
For high-pressure locations: treat the undersides of fascia, deck joists, and porch ceilings with permethrin spray in April-May before bees become active. Residual contact deters new gallery excavation.
💡 Pro Tips
💡 Carpenter bee females (the wood-borers) are docile — they almost never sting unless directly handled. Males hover aggressively but cannot sting
💡 The same holes are reused by new females year after year — early treatment prevents expansion of existing galleries
💡 Cedar and redwood are somewhat less preferred than pine and other softwoods, but no wood is immune to carpenter bee attack
✅ How to Know It's Working
Pest control success is measured in weeks, not days. Here's what to look for:
- Week 1–2: You may see increased activity as pests are flushed from hiding. This is normal.
- Week 2–4: Activity should drop noticeably. Bait traps or sticky monitors should show declining counts.
- Week 4–6: New activity near zero. Any resurgence means a population was missed or re-introduction occurred.
💡 Monitoring tip: Place sticky traps in corners and along walls before you start treatment. Counting catches weekly gives you objective data on whether the population is declining.
👷 When to Call a Professional
DIY is appropriate for small, contained infestations caught early. Call a licensed professional when:
- You've tried DIY twice with no lasting improvement
- The infestation involves a wall void, crawlspace, or area you can't safely access
- There's a health risk involved (hantavirus, anaphylaxis risk, etc.)
- The problem covers more than one room or a large outdoor area
- You have children, elderly, or immunocompromised individuals in the household
⚠️ Rule of thumb: If you've spent more on DIY materials than a professional visit would cost, it's time to call.
❓ Frequently Asked Questions
When is the safest time to remove a wasp nest?
Treat wasp nests at dusk or after dark when all workers have returned and are less active. Temperatures below 50F further reduce activity. Never attempt removal during daytime when guard wasps are most aggressive.
Should I remove the nest after treating it?
Wait 24-48 hours after treatment to confirm all wasps are dead. Watch for returning wasps. Wasps will not reuse an old nest, but the same location may attract new queens in spring, so removal is recommended.
What wasp spray is most effective?
Aerosol sprays with pyrethroids that shoot 15-20 feet work for accessible nests. For ground nests, pour liquid insecticide into the entrance at night. Dust formulations like Delta Dust work best for wall void nests.
How do I prevent wasps from building nests?
Apply residual bifenthrin spray to eaves, soffits, and porch ceilings in early spring before queens begin nest-building. Remove abandoned nests from previous years and seal gaps in siding and soffits.