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Carpenter Bee Control


Before taking any actions to kill carpenter bees, you should first assess whether or not it's really necessary to do so. Carpenter bees are useful insects and efficient pollinators. They're also non-aggressive, so unless you are allergic to bee stings and can't afford to take any chances, they present little threat to humans.

So if the bees are infesting an unimportant piece of wood (such as a piece of fascia board on a dilapidated shed that you wish would fall down anyway so the county would stop taxing you for it), then the best approach may be to simply ignore them.

When it is necessary to kill carpenter bees, then they are not particularly difficult to kill. Like bees in general, they are highly susceptible to a wide range of insecticides. The problem lies in getting the insecticide into the holes.

Remember that the entrance hole is just that - an entrance hole. The actual gallery may extend a foot or more in either or both directions, along the line of the wood's grain.

Sometimes the tunnels may also "branch off" into new tunnels inside the wood, if it is of sufficient thickness. And because the tunnels are packed with eggs and wax, any insecticide applied is not going to penetrate very far.

Furthermore, carpenter bees often drill holes in hard-to-reach areas that make treatment even more difficult. Spraying the surface of an infested piece of wood will have little or no effect. You have to get the chemical into the hole.

Do-It-Yourself Carpenter Bee Control

That being said, if you want to try to kill your carpenter bees yourself, you can use any insecticide labeled for carpenter bee control.

One good choice would be an aerosol insecticide with a "straw" or "tube" applicator that you can use to inject the insecticide directly into their entrance hole. This will get the most effective kill ratio, if you know the female bee is inside the gallery. This is also just about the only way she will get a lethal dose of insecticide, which helps to insure that she just won't abandon the treated gallery only to construct another.

You can also use a dust insecticide that is labeled for carpenter bees, like Delta Dust. Inject the dust directly into the entrance holes.

Dusts tend to be more hazardous than other types of insecticides. They will readily drift away from the target area in the slightest breeze, and may blow back into your face from the holes you are treating. Use extreme caution, follow the label instructions, and be sure to wear a respirator when applying any dust insecticide.

Don't expect your treatment to work the first time. To kill an entire nest, you will likely have to treat the same holes repeatedly throughout the season, every few weeks, until the weather gets cold. This is because insecticides will not kill eggs that are already in the galleries.

Once the fall comes around, plug all the entrance holes with silicone caulking or a quality wood filler (not polyurethane foam) and finish all of the exposed wood surfaces with a good, oil-based paint or stain. If you can, remove the wood and finish the "back" sides, as well. Carpenter bees are less likely to attack wood that's been treated with an oil-based coating.

When replacement of the wood is necessary, use treated lumber whenever possible.