Carpenter Bee Control
Eric Ronning
Identification
Carpenter bees have relatively hairless, shiny, black abdomens (butts) that often reflect colors like blue, purple, and green. Males have white faces and defend their galleries quite aggressively. Luckily, they don't have stingers and cannot hurt you. Females have black faces and can sting but almost never do.
Carpenter Bee 1
Carpenter Bee 2
Carpenter Bee 3
Carpenter bees (a.k.a. wood bees or borer bees) are best known for chewing circular holes in your wood. As there are seven species found in the U.S., there's some slight variation in hole size, but they generally have a diameter of about one-half inch. Carpenter bee holes often have little piles of sawdust below them and yellowish brown poop streaking down from them. Also, they only go into the wood about an inch before taking a sharp ninety degree turn away from the entrance. Once these tunnels (called galleries) turn from the entrances, they generally go on for another four to eight inches. In most cases, carpenter bee damage is minimal and won't cause any structural instability. However, if carpenter bee infestations are left unchecked, serious damage can occur, and carpenter bee extermination becomes necessary.
Controlling Carpenter Bees NOW!
Exterminate carpenter bees with boric acid. Boric acid dust, made from the mineral borate, is a fantastic carpenter bee killer. Using a bulb duster, apply a puff or two of boric acid into each carpenter bee hole you can find. Do this during the day when the female is out. Boric acid acts both as a stomach poison and as a desiccant which dries out and kills bees. Once you're relatively certain that the female has walked through the boric acid, leave the dust in there and seal the hole (see below). Leaving it in there will help to ensure that any juveniles that might hatch will be forced to come into contact with the boric acid.
Sealing holes. Holes should be sealed in the evening after the bees have returned and have walked through the dust. Wad up a piece of aluminum foil or steel wool and quickly (so as not to get stung) shove it into the hole. Ram it in there good and tight with a stick, pencil, etc. Leave enough space between the wadded up foil/steel wool and the hole's opening, so you are able to plaster some wood putty in there. The reason for the foil/steel wool is that the female won't be able to get through that to chew through the putty. To lessen chances of getting stung, some people choose to wait until the next day to seal carpenter bee holes.
Exterminate carpenter bees with insecticidal dusts. Boric acid is not the only dust that will kill carpenter bees. You can also use dusts such as Apicide (active ingredient: carbaryl), Delta Dust (active ingredient: deltamethrin), or Tempo (active ingredient: cyfluthrin) in the same manner as you would boric acid.
Kill carpenter bees with spray insecticides. Many spray insecticides that you mix at home and apply with your own sprayer can control carpenter bees not only with their quick knock-down power, but also with long-lasting residual protection. Look for brands with the active ingredient cypermethrin, like Demon WP and Cyper WP, or those with the active ingredient lambda-cyhalothrin, such as Cyonara 9.7 and Demand CS. With reviews as good as the ones these products have received, any one of them will help you to get your carpenter bee problem under control lickety-split.
Control carpenter bees with aerosol sprays. Don't feel like mixing your own? No problem. Most apicidal sprays will work just fine for killing carpenter bees. While a majority of the cans you'll find at the hardware store that are labeled for killing bees and wasps (Raid, etc.) will do the trick, I recommend going with something a little more powerful like CB D-Foam (active ingredient: deltamethrin), Microcare Aerosol (active ingredient: pyrethrins), MotherEarth 2% Py Contact Aerosol (active ingredient: pyrethrins), PT 221L Residual Aerosol (active ingredient: lambda-cyhalothrin), Cy-Kick Aerosol (active ingredient: cyfluthrin), or Propoxur Aerosol (active ingredient: propoxur). All of these are easy to find through online retailers and kill carpenter bees like nobody's business.
Control carpenter bees with carpenter bee traps. The most common and effective type of carpenter bee trap is known as a chamber trap. These traps are boards with pre-drilled holes in them that lead to an adhesive-coated chamber. Once bees climb inside the holes, they get stuck to the adhesive and die. These traps come in a couple of different styles: one for attaching to fascia and one for attaching to soffits. The reason these traps work so well is that carpenter bees are lazy and are far more likely to use a preexisting hole than to put the work into drilling a new one.
Kill carpenter bees with a vacuum cleaner. It sounds a little odd but apparently this method works quite well for controlling carpenter bees. After putting proper clothing on for protection against bee stings (layers of thick, loose-fitting clothing, gloves, hats, etc.), grab a shop vac or a vacuum cleaner with a hose, attach a narrow hose attachment to it, press it against the holes, and start sucking. This method is best performed in the wee hours of the morning before the bees have left the gallery or at night after they've returned.
Avoid Future Carpenter Bee Infestations
Seal old holes in the early spring before carpenter bees arrive. Carpenter bees reuse old holes and galleries. They should be sealed prior to the beginning of April.
Keep your house freshly painted. Carpenter bees are partial to unpainted, weathered wood. Paint your house/shed/garage/whatever at least once every three years. Leave no surface bare.
Build or rebuild with hardwoods and/or green treated lumber. When replacing wood damaged by bees, use hardwoods like maple and oak. When building decks, patios, etc., use green treated lumber.
Get rid of flowers and flowering plants. Carpenter bees like flowers almost as much as I like chicken wings. Removing them will help you with getting rid of carpenter bees.
Choose your siding wisely. Replacing wood siding with either seamless vinyl or aluminum siding will allow you to permanently block carpenter bees from drilling holes into whatever surface you affix it to.
Wrap or cover exposed wood with aluminum flashing. Covering exposed wood such as eaves, the back sides of trim pieces, and support beams completely cuts off the carpenter bees' access to the wood.
Natural Carpenter Bee Control
Repel carpenter bees with almond oil. The chemical component benzaldehyde, found in almond oil, is a natural carpenter bee repellent. Spray or paint almond oil on surfaces likely to be damaged by carpenter bees. Just be warned that almond oil can be harmful if swallowed or repeatedly inhaled.
Kill carpenter bees with diatomaceous earth. DE is an insecticidal dust made from the ground-up fossilized remains of ocean diatoms. DE is sharp. When bees walk through it, they get cut up, they dry out, and they die. Apply DE in the exact same manner as you would boric acid (left).
Lure carpenter bees to different areas with bee blocks. If you don't want carpenter bees damaging your property, but you don't want to kill them, homemade bee blocks are a good option. By taking a few 12‒24 inch chunks of 4x4 cut from untreated softwood like cedar or pine and drilling two to four ⅝-inch-wide and one-inch-deep holes into each side and hanging them in shaded areas away from your house, carpenter bees can be lured away from the areas you are trying to protect.