St Louis Pest Control Blog

St. Louis Wood Destroying Insects – Carpenter Bees

Spring is here and the Carpenter bees have already been found buzzing around homes and decks.  Normally you don’t see them until the later part of Spring but Mother Nature is changing the rules once again.  If you have ever owned a cedar sided house or deck, you know exactly which insect I am blogging about.  But for those of you who don’t know the destruction that these bees can cause, consider yourself lucky.  St. Louis Pest Control operators and the D.I.Y.’ers battle these non-social insects every year.  Because these bees are not social (meaning they do not live in a colony like honey bees), it makes the task very difficult to eliminate  the problem in a single treatment.  If  the Carpenter bee did live in a colony, anyone could make a direct application into the nest and successfully kill all the bees in one shot.  Unfortunately for us, they do not.  So with that in mind, any areas of activity that you would have treated on one day you could potentially have just as many (more or less) Carpenter bees (completely different from the bees already treated) come back to your home starting the process all over again.

Why are they attracted to some homes and not others?  A lot of it has to do with what type of  material were used to build your home but in some cases it is just purely bad luck.  An adult female Carpenter bee has two main missions in life, one is to drill out an almost perfect 3/8″ hole (often confused with a hole a drill bit would make) and gallery in any accessible wood (preferably a soft wood, such as pine or cedar).  And secondly, to mate and then use the gallery to lay her eggs so that they have a safe place to mature. The male Carpenter bee on the other hand only wants to find a female bee to mate with.  You often find one or two steadfast male Carpenter bees hovering around the area where the female has burrowed into the wood trying to  protect his  territory.  When we get close to this area you will often find the male Carpenter bee flying close to your head in a show of force.  Luckily for us, the males are without a stinger and cannot do anything but try to intimidate.  The female bee does posses a stinger but rarely uses it.  But,  if  for some reason you do get stung by a Carpenter bee, it will be only be one bee doing the stinging instead of a swarm attack like hornets or yellow jackets.  In my experiences with Blue Chip Pest Services, I only know of one technician being stung in the last 10 years by a Carpenter bee, and it happened when the the technicians accidentally had covered an exit/entrance hole with his hand while bracing himself under a deck.

How can we use this information to our advantage?  Now that we know that Carpenter bees are fairly docile and not at all aggressive like some of the other social stinging insects like Bald Faced hornets or Yellow Jackets we can treat with some confidence that being stung is not a likely outcome.  The hardest part of the treatment and control will be the ability to locate each and every hole and treating it.  The best treatment option is to use a insecticide dust with a hand duster.  There are several dust options available but I prefer Delta dust because it stays highly effective  in all types of weather conditions (wet or dry).  Once you have filled the hand duster with a few ounces of dust you will want to put a washer or a few pennies into the duster to create some agitation.   Shaking the duster now with the objects you have chosen with help it fluff up the dust so that it can flow easier when compressed.  A few puff into each hole will do the job.  Just make sure that you have angled your duster in more than one direction as some Carpenter bee holes go left and right with the grain of the wood.  It’s important not to plug up the Carpenter bee hole after treatment.  Wait at least a few days to allow the adult bee to enter hole and pick up a lethal dose.  When it is time to close up the holes make sure that you use a paint-able caulk or putty if you are planing to paint the wood surface.


If Carpenter bees are left untreated you may find damaged wood like pictured here from Woodpeckers.  Woodpeckers hear the moving larval stage inside the wood galleries and instinctively try to open them up for a quick meal.   So with this mind, it is far less costly to treat your home for Carpenter bees than it is to hire someone to replace unsightly damaged wood.  The most important step is to address the problem quickly before things get out of hand.

Please call us if you have any questions or concerns regarding these pests at 636-343-7900 or go to for more information regarding our service options.


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