Signs of Carpenter Bee Infestation
The most telling signs of carpenter bee infestation are the presence of half-inch round holes in dry, unfinished wood, with piles of sawdust underneath. Also look for dirty yellow streaks of fecal matter staining the wood below the hole. If a given hole is presently occupied, you will likely find the male buzzing around you when you are near that hole. A single pair of carpenter bees occupies each nesting hole, with the female boring galleries and the male standing guard outside.
Step 1) Prevention
Don't invite them- make wood unappealing:
- Carpenter Bees tend to target the same nesting sites year after year. Since carpenter bees prefer bare, unfinished wood, one preventative measure would be to paint and then finish (with varnish or sealant) wood that has been repeatedly infested in years past.
- If possible, exterior parts of buildings, decks, outdoor furnishings and other wooden structures should be constructed out of hardwoods.
- Fill cracks and depressions in wood surfaces with wood putty so they are less attractive.
- Fill vacant holes present in wood with steel-wool or STUF-FIT Copper Mesh to prevent their reuse. Wait until after bees have emerged before filling the tunnels. Once filled, paint or varnish the repaired surfaces.
Apply residual treatments in early spring, before active nesting:
- Using a Chapin SureSpray 1 Gal Sprayer, apply a liquid residual insecticide to all wood surfaces you want to protect. We recommend Demand CS, or Demon WP Insecticide. Both work well against carpenter bees. Demon WP has a higher concentration of chemical but may leave a messy residue on dark surfaces. Where you are concerned about the product being seen, Demand CS has a cleaner residue.
Step 2) Dusting the Nest
If you have an existing infestation of carpenter bees, it is not enough to kill the buzzing adult males outside the nest, or even the adult female bee that is laying eggs. Eventually, the larvae inside the gallery will hatch (usually within 3 months), so you need to attack the nest directly. Then when the larvae do hatch, the newly emerged adult bees will fly through the dusted gallery, getting some of the dust on their wings and bodies. As the chemical is absorbed, the carpenter bees will begin to die.
First, get rid of the adults with a knockdown spray:
Apply dust directly into the nesting gallery, using a hand duster:
- You will first need to get rid of any adult males buzzing around the nests so that you can freely treat the nesting holes. This is easily accomplished using a quick knockdown spray, such as PT Wasp Freeze Aerosol.
- The aerosol should also be directed into the nesting holes to flush out and kill the female carpenter bee, if she is exposed.
- After carefully reading the product label, apply Delta Dust Insecticide (effective 6 to 8 months) liberally and deeply into each nesting gallery using a Centrobulb Duster.
- DO NOT SEAL OFF NESTING HOLE while larvae remain alive in the nest. Wait 3 months after the dust application when you are sure all the larvae have hatched and died. If you seal off the hole before all the new bees have died from the chemical, they simply bore new holes in order to escape the gallery and not have an opportunity to pass through the dust on their way out.
Step 3) Apply a Liquid Residual
If you missed the opportunity to apply a liquid residual in early spring as part of the prevention step (see step 1) and are now facing a carpenter bee infestation, now is the time to apply a liquid residual. This should be done after you have dusted inside the nesting hole.
Apply a liquid residual insecticide to the infested wood surface:
- Using a Chapin SureSpray 1 Gal Sprayer, apply a liquid residual insecticide to all infested surfaces as an added protection. We recommendDemand CS, or Demon WP Insecticide. Both work well against carpenter bees. Demon WP has a higher concentration of chemical but may leave a messy residue on dark surfaces. Where you are concerned about the product being seen, Demand CS has a cleaner residue.
Step 4) Wait 3 to 4 months until no activity is noticed. Seal off entrances to nesting galleries.
If you seal off the entrances to the carpenter bee nest too soon, the larvae that hatch several months later will simply bore new escape routes, passing by the "dust trap" that has been set for them in the original hole. Instead, wait 3 to 4 months after your dust and residual application to seal off the nesting holes with wood putty, steel wool, or STUF-FIT Copper Mesh.
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