Carpenter bees have made their return

Posted 3/31/19

I have finally figured out what to do with my old tennis racket.  I still have it back from the “old college days” when I used to consider myself at least semi-athletic.  One look at my …

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Carpenter bees have made their return


I have finally figured out what to do with my old tennis racket.  I still have it back from the “old college days” when I used to consider myself at least semi-athletic.  One look at my waistline now though and you will know that my tennis racket has been in the closet for quite some time.  I think it shows great promise as a bee swatter, if I could only find it!

Just this week I have started noticing an increase in activity of large black bees (that resemble bumblebees) hovering around eaves, decks, and wood siding of your homes, sheds, and outbuildings.  The bees that make holes in your wood structures are not ground dwelling bumblebees; rather they are actually called carpenter bees.

Carpenter bees are among the largest of bees, often growing to 1½  inches long.  At a glance they do look like bumblebees.  Again, though, bumblebees nest in the ground and carpenter bees nest in the holes and tunnels made in wood above ground.  Carpenter bees also have a very shiny abdomen while bumblebees have tiny hairs covering their abdomen. 

Male carpenter bees patrol and defend their territory very fiercely.  They often hover around and I’ve even seen them “dive bomb” bystanders who get too close to their nesting activity.  The only problem is that the males are absolutely harmless.  I know this for a fact because they do not have a stinger! The male carpenter bee has a cream white colored spot around their mouthparts, and for this reason many people refer to them as “white faced bees.”

Female carpenter bees are another story altogether.  They can sting with such intensity that you think they come from another dimension. Fortunately, they are not very aggressive and will usually only sting if they are caught or disturbed. They should simply be avoided if at all possible. 

This is one fault of my tennis racket control theory.  I’m a bit rusty with my racket and the bees tend to get aggravated about the forth or fifth swing.

I remember years ago as a kid, I was going to show off my bravery for some friends by catching a “bumble bee” in my bare hands.  I tried and tried and actually was finally successful in catching the bee.  Well, what I misidentified as a harmless male carpenter bee was actually the female (without a white face). 

It only took a couple days for the redness, swelling and pain to be gone but till this day my friends still from time to time ask me about the time I “caught the bumble bee in my bare hands.” 

Carpenter bees tunnel into wood in order to lay eggs.  Bare, unpainted, weathered softwoods are preferred by carpenter bees.  Redwood, cedar, cypress, and pine are particular favorites.  Painted or varnished wood tend to discourage them, especially if there are other more suitable areas nearby.  Pressure treated lumber is also less likely to be damaged by carpenter bees, but that certainly doesn’t mean that it is immune!

Carpenter bees overwinter as adults in old nest tunnels.  After mating, the females excavate tunnels in your wood structure and lays eggs in them.  The entrance hole is just about perfectly round and about the size of your finger.  Coarse sawdust, the color of fresh cut wood, is often seen beneath the entry hole.  Burrowing sounds may even be heard within the wood.  The female carpenter bees may excavate new tunnels or enlarge and reuse old ones.  Serous structural damage can result when the same piece of wood is worked year after year.

The best time to control carpenter bees is before tunnels are fully excavated.  For homeowners, liquid sprays of carbaryl (Sevin), or pyrethroids (there are many available) can be applied directly into nest openings, or even sprayed as a deterrent onto wood surfaces attracting large numbers of carpenter bees.  Residual effectiveness of such applications is only a few days at best, so the treatment may need to be repeated.  Tunnels that have already been excavated can also be treated with an insecticide.  In these cases dust products are more effective.  Sevin dust can be “puffed” into the nest opening.  Fairly inexpensive “dusters” can be purchased at many farm supply stores or even lawn and garden centers.  Boric acid powder can also be effective for those who do not wish to use traditional chemical insecticides.  Boric acid powder is generally slower to work, however.  

Finally, the over-the-counter wasp and hornet sprays are effective if only a few nest openings are detected. Although carpenter bees are much less aggressive than wasps, hornets, or most other bees, the females can give you a sting that you will remember for a long time (the white faced males have no stinger and thus no ability to sting).  I can tell you that with absolute certainty based upon my experience with them.  Treatments are best performed in the late evenings and while wearing protective clothing.

Leave the treated holes open for a few days after the insecticide application to allow the bees to contact and distribute the insecticide throughout the nest galleries.  Then plug the entrance holes with a piece of wooden dowel coated with carpenters glue, wood putty or other sealant.  Plugging the holes and sealing them will prevent future carpenter bees from reusing the tunnels and it will also protect against moisture intrusion which can cause the wood to decay.

Carpenter bees prefer not to tunnel into painted wood. Therefore, a more permanent solution is to paint the unfinished surface especially those with a history of being attacked by carpenter bees. This is by no means a guaranteed method since carpenter bees will attack just about any wood. I once had a carpenter bee that even tunneled into the handle of my wheel barrow!  

Wood stains and preservatives are even less reliable than painting, but may provide some small degree of protection. To further discourage nesting, garages and outbuildings should be kept closed when carpenter bees are actively searching for nesting sites.  The annoying flying and nesting activity usually subsides by late May or early June. 

Until then, don’t be surprised if see me with my tennis racket in hand swatting at the carpenter bees…..who knows, maybe with enough practice and if the carpenter bees last long enough I can even get back into my old college days form.