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Last Update:  11/11/15
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||  Carpenter Bee Damage  ||  Doing it Yourself  ||  How We Do It  ||  Preventing Carbenter Bees  ||

carpenter bee
arpenter bees, Xylocopa virginica is the predominant species around here, are solitary
bees.  That is, they don't live in a "hive" such as honey bees do.  They do, however, tend to accumulate in certain areas.  In this area of the Delaware Valley, they are known to attack any unpainted or unfinished wooden items.  While the females do have a stinger, they are very docile and are not known to sting people, even when disturbed.  The males, as with any bee, wasp or hornet, have no sting mechanism.

You can completely ignore the ones that "buzz" you, they're the males. The females are much too busy getting their galleries ready to deposit their eggs to bother with you. Females will work all summer, you just won't notice them. The woodpeckers will, however.
I hate the females!

bumblebee - CLICK for large image
Carpenter bees are bigger and much more robust than the bumblebees.  Female bumblebees can sting and female carpenter bees have the equipment, but almost never do.  (I don't think you should risk handling any kind of bee, however!)

In the springtime, the males actively search out the females, and hang around where the females have found some unfinished wood.  In nature, this is a dead tree or tree branch, but modern building techniques, (and modern paints and finishes) cause the problem. Most of the congregating bees you see in the early spring, hovering around, will be those males. They hang around, waiting for the females, (just like all males) they are very territorial, and will confront you whenever you enter their territory.  Male bees are incapable of stinging, and are only checking you out.  If you stand still for a minute or two they will forget you are there and leave you alone - unless, of course, you happen to be a female carpenter bee.

It happens because builders and painters often don't paint the areas of your home that you don't normally see. Carpenter bees can get into very small areas, and will seek out the unpainted wood surfaces and bore their holes, (perfectly round holes, about 3/8ths of an inch in diameter) using these galleries to cache several eggs that will eventually hatch into more bees.

These same bees will hibernate in these same galleries over the winter, so they do tend to accumulate, after a few years, into more and more bees, until you might think they will take over the whole place.

The bees can find these unpainted areas and will bore holes into it, and after a few years you will find that it is full of holes or gouges that emerging bees have made in the wood. Fortunately, these infestations are self-limiting, and carpenter bees do not attack the inside wooden structure.
Carpenter bee damage

Although, technically, they are a "wood boring insect," they are not really considered a true structural pest.  They will not spread throughout the structure, but they will attack any outside wood that is not painted or finished.  Around here, they frequently attack the back side of fascia boards (installed as trim) which is routinely not painted.  Sometimes the holes are not visible, and all you can see is the ejecta from their boring.

You can paint.  You must paint everything, even the areas you don't see, such as under window sills and under bannisters and railings.  Use a GOOD exterior primer, TWO coats, follow up with at least one coat of finish.  Covering wooden components with aluminum sheathing will work only if done correctly.  This means that you must eliminate any spaces where the bees will find the wood.  They can squeeze through incredibly small places, so you have to be very thorough.  Spaces or holes a quarter of an inch or larger will let these bees through.

Usually these magic ingredients are expressed in a number - "PDQ-4 additive" or some such thing.  The magic ingredient is diazinon.  It has mixed results, if used as directed, and as a result, many paint suppliers have been recommending doubled amounts of the additive, for better control.  I'm not sure if this is legal, (or even advisable) especially since success is so spotty.   They claim the effect of the insecticide will last "for up to" four years.

Don't count on it.

If the insecticide, in a real world situation, really worked for four years, I would be afraid of it.  And if the "special paint" gets the sun or gets wet, you can throw out the four years. Make that, probably, less than a year.  So if you use these paints with insecticidal additives, the best place to use them would be, naturally, out of the sun and away from water.  In this situation they may help, but they certainly won't be a cure-all.  They'll also be quite expensive.  Especially if you "double-up" on the magic ingredient.

You should use pressure-treated wood in any outdoor project such as decks and playhouses.  Or paint it with at least four coats of paint, on all sides.  The first two coats should be an exterior primer, then two finish coats.  Remember, paints now have no lead or mercury in them, and offer much less protection than paints of the past.  You will also have to repaint every few years.  Pressure-treated wood needs no paint, but can be painted if you wish. Cedar does offer some protection, but even cedar is attacked if the conditions are right.  California redwood is often attacked by the eastern carpenter bee, redwood is expensive and the wood very soft, suitable more in a decorative situation rather than a structural one.

Nowadays, even trim (for windows and doors) is available in pressure treated versions. Mount your trim pieces, especially stair components, kick plates and sill plates, with non-rusting screws, not nails.  Resist the temptation to erect or buy one of those fancy redwood swing sets they sell.

The bees just LOVE those $2500 redwood swing sets....
The bees will make short work of it if you're not vigilant, and the kids won't want to go near it with all those bees buzzing around, even though the bees won't hurt the kids.  Forget redwood, use pressure treated wood for your swing set and paint it if you want it to look like redwood.  The kids won't care.

Well, not a whole lot, it depends on how long the bees have been there.  But the first order of the day would be to STAIN it.  With an exterior oil-based stain.  And you'll probably have to do this just about every year, some stains are better than others.  If you know the manufacturer of your swing set, contact them for specific recommendations.  It might be a good idea to do your staining in the spring, before the bees are in evidence.  A fresh coat of the stain will definitely help keep these bees at bay.

Sometimes, depending on the area you want to protect, you can use common insect screening to keep these bees from getting into areas where there may be unpainted surfaces, such as behind fascia trim boards or other places where it might be difficult or impossible to paint.  Just cut strips of metal insect screening, (don't use the fabric or plastic type) get up on a ladder and wedge or staple them into place where the bees are working. You can do this with the bees there.  They won't "sting" you such as a wasp or other stinging insect.  I have done just this procedure with 50 bees buzzing around me and I've never been stung by a carpenter bee.  However, don't forget - you are working in an area where wasps and all those other stinging insects reside, so be sure you're clear of those, or take care of them beforehand.

You can also cut strips of screening to fit the areas where the bees attack, and just paint right over the screening.  After a few coats of paint, the screening is invisible except under close inspection.  Use metal, not fabric screening.  The same paint rules apply here, you must use at least two coats of exterior primer, and another two coats of finish.  That's FOUR coats, and don't use the cheap paint from Home Depot.

The treatment of carpenter bees is easy - sort of.  What makes them difficult is that sometimes the bees are up high and out of reach.  Each female bee has her own gallery and usually enters through her own entrance hole.  Sometimes a few carpenter bees will use the same entrance hole, making their own galleries.  To treat effectively, you must find each entrance hole, treat each one, (preferably with the bee inside) waiting a few days to see if you are successful.  Once you know each hole is inactive, just before the first hard freeze, you can caulk the hole, and paint the area.  You may have to do this several years in a row to find all the active areas.  Also, the bees will always be looking for new areas. They seem to prefer southern or easterly exposures, but will take advantage of any unfinished wooden surface.

First of all, don't expect the exterminator that "sprays the wood" will keep these bees away from the wood they are attacking.  You'll have to do this every year.  Unfortunately, at present, there are no really good chemicals or insecticides, (that are safe for you, me and the wood) that you can apply to keep these bees away.  

To have any effect at all, any insecticide you use must be injected DIRECTLY into their galleries - not applied to the surface.  So you can't just rig up the hose with the same device you may use on your lawn, and spray the house. Some of those chemicals may affect paints or siding - or both.

And, of course, don't use marine paints.  Not only are they outrageously expensive, but they also contain more toxins than you'd care to be associated with.  If toxic paints are discovered on a house, it might have to go through an expensive removal process before the house can change hands.

Also forget the foam insulation stuff that comes out of pressurized cans and expands to fill cavities.  Carpenter bees go through this stuff like Lady-Be-Good.  This is NO good. Some even say on the label that it will keep insects out.  It will not keep the carpenter bees out, I don't care WHAT they say.  (Next time I see this, I'll get a picture.)

You can use any insecticide labeled for carpenter bees.  The best would be a product supplied with a "straw" so you can 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.
If you're using any kind of insecticide,
follow these directions.

As your tool of choice, you can even use WD-40, an all-purpose lubricating oil, that will also kill a carpenter bee.  You can also assume that the female carpenter bees are almost always in their galleries at night, so you spot the active holes in the daytime, and treat them at night, when the sun has gone down, wait til it's pitch dark.  If you're not sure if a hole is active, stuff it with a bit of wet kleenex and then check back in a couple of days.  If you have a lot to do, don't rely on your memory, pencil-mark the date beside each hole.
You can use this, too...

(Does this sound like a pain in the neck?  It most certainly is.  But it's the best way to make sure you take care of all the areas.)

After your treatment, and after the bee has backed out of her gallery and you have killed her, use the wet kleenex trick in each hole, then check back in a day or two to see if it is still active. Check again every few days, then repeat as necessary.  You can see how this job might take awhile, and is best done by YOU - after all, you live there, and you have your best interests at heart.

If you start after these bees early in the season, before they have completed their galleries, you will have less to worry with the eggs they leave.  To help destroy the eggs, (no chemical will penetrate that far) you can rig up a length of stiff wire and ream out each gallery. Some galleries will always be unreachable and you probably won't be able to addle all the eggs anyway, but it may help.

Remember, since the bees don't actually EAT the wood, pressure treatment may not even deter these tough little critters.  Another little trick is to soak a cotton ball in xylene (finger nail polish remover) and jam it into the galleries, to help kill the eggs.

HOW I ACTUALLY DO IT - (if I do it)
Naturally, I check all the outside areas for evidence of the bees and any other stinging insects that I have to take care of first.  My preferred method for the carpenter bees is insect screening.  I cut strips and customize them to the individual area at the workface. Sometimes, instead of strips, I roll the screening into narrow cylinders, and wedge them into place.  If I happen to see a female bee enter a gallery, I will treat the gallery while she's in there and continue with the screening process.  Everything has to be checked at a later date, as the bees are quite robust and can possibly dislodge the screening or find another way in. You get better at it after a few houses.

Now, if you want to pay me (or my men) a nice, fat hourly fee to do this, we'll be happy to oblige.  But I think you can do this just as easily as we can, (and a whole lot cheaper) besides, I just gave you the whole secret on dealing with these things.....  So all you need is a ladder, (maybe) some screening, a can of WD-40, (maybe) and a little intestinal fortitude.

Whatever chemical you use, make sure you use glasses or goggles so you won't get any spray-back into your eyes.  Do I need to say, "Be careful on ladders?"
And if you're using any kind of insecticide,
follow these directions.

We can do this for you!
For residential chemical treatment of these bees, in situ, we will use a special piece of equipment for dusting the trim in those high, inaccessible places that are difficult to get to without special ladders or scaffolding.  This equipment allows us to inject the dust into areas we can't get to easily.
Treating carpenter bees up high

Would you like us to send you a price quotation for any of the services described on these pages? Just fill out this form and we will reply by email, with a quotation tailored to your personal requirements. Please include your phone number if you wish us to call you.

BTW, don't use WD-40 on regular bees (yellow jackets, honeybees, wasps or hornets) it just doesn't work fast enough to disable them, and will only make them angry.  Professional help is usually needed here, it can get dicey.
bald faced hornet nest

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