Carpenter Bees in Maryland: Public Enemy #1 or Just Misunderstood?

Spring has (finally!) sprung here in mid-Maryland, and Mother Nature is doing her work.

Image: Cobra Pest Control

With the emerging greenery, flowers, and warm temps, come the creepy crawlies and fearless flying insects that we expect to see. Stink bugs, ants, spiders, and bees are back in force, in particular, the emerging carpenter bees, doing drive-bys past my head every single time I go let out the dog or attempt to pretend I like to garden. Our backyard (and even parts of the front yard) this time of year seem to be taken over in force by these carpenter bees--at least the airspace, anyway.

Yes, I am guilty of waving my arms, channeling my inner sailor with some colorful rapid-fire bee defense profanity, and even shamelessly swinging a towel around over my head like a pathetic human helicopter ninja when one of these guys comes at me. Hey, I own it.

Apparently though, diveboming intruders like me is just "what they do." Contrary to what my instincts tell me every single time, they are not trying to dispatch me. In fact, I have now begun to understand that stinging by carpenter bee is very rare--only the females can, and hardly ever do. The REAL threat to us human types comes in with the wood damage that can be done. Softer, untreated wood is their filet mignon. But make no mistake--they will go for a New York strip by way of your stained deck posts, a delectable T-bone fence rail, or even a wood patio furniture sirloin. Even cedar, long thought to repel most pests, has something to fear by these guys. Though they aren't actually "eating" the wood, just tunneling into it for the good of their species.

As busy flying critters these guys are excellent pollinators. They do good work, and we all benefit. But in residential settings they also destroy valuable property, and homeowners often find their hand forced into taking action. Lenders quite frequently require a WDI (AKA "Termite Cert" or Wood Destroying Insect certification) to take most loans to closing. Termites, carpenter ants, and these bees are what they are inspecting for, because the reality is that their natural behaviors can easily be the cause of thousands of dollars in damage to a home.

Carpenter bee 101... 

Image: Cobra Pest Control

• Though they look like bumble bees to many people, the carpenter bee abdomen is bare and shiny black. These guys are not as fuzzy/hairy as bumbles. 
• They are usually about 1" long and their large wings make a pretty intimidating sound, so pretty scary to most of us easily frightened bipeds. 
• The males have an almost square white marking on their faces. I have seen this marking. Had a good old fashioned standoff six inches from my face just the other day... He won. 
• Why do I assume said "bee" was a "he?" Because the male carpenter bees--again, who actually have NO stinger--are the ones up in your face. This behavior is by design to scare intruders off from the female doing her work in the tunnel, thereby looking as aggressive as possible. Especially to a person moving quickly or waving their hands in the air like a maniac. Then they come SUPER close--into that personal space bubble--causing panic. And more ninja arms. And some shrieking by even the toughest of so-called grown men <cough - my husband did what? - cough>.
• The females do have stingers, but their work finds them most always down in the tunnels or gathering pollen, not dancing on air by your head. Even then, females are known to hardly ever actually sting--reports of stings by carpenter bees seem to only occur when someone is actively treating the holes/nests or handles one directly. Um... duh?
• As mentioned above, they do not actually "eat" the wood in question, but they absolutely DO drill holes into wood. A lot. This is to make tunnels for laying eggs and rear their young.
• The tunnels they excavate can be extremely long, as the female will create individual bee-rearing chambers, one for each of her anticipated young. Cute little bee bunk beds, if you will. 
• Once mama bee creates the space, she will then deposit an egg, bring in a mass of pollen for the larvae to feed on, and then seals off the chamber. Then she moves on to the next baby-bee-making chamber. Repeat.  

Assessing the damage...

Image: Cobra Pest Control

• Observe the bees just before sundown as they pack it in for the day. Carefully explore the wood around your home, and you will find perfectly round holes about 1/2-3/4" in diameter. You will likely also notice saw dust trails near these holes, and yellow staining (yup--that's bee #2) directly below.
• These entry holes are just the beginning, unfortunately. The tunnels/chambers inside can be extensive, and can run through the entire length of a piece of wood. 
• Carpenter bees not only lay eggs in these chambers, but after the larvae have flown away, they will clean them out and take residence there during the colder, inactive months. 
• It only takes a year or two to have a full blown infestation in a residential setting.

Treating and preventing...

• They tend to prefer the more elevated areas of the house, so effective identification and treating may require some tall ladders and some bravery--or better yet, a licensed professional to do the job. Treating can make the nesting females aggressive, and angry bees + a tall ladder = elevated risk of a pretty serious insurance claim. I'm no actuary, but... sounds like a recipe for disaster to me.  
• Treatment involves injecting material (dusts, insecticides, etc. - consult a professional for recommendations) directly into the openings, killing any bees or larvae inside, and creating a residual affect that will kill the returning bees. They will also recommend you fill the existing holes with wood putty or a similar substance. 
• Some exterminators recommend applying a repellent material to wood that is repeatedly infested, but this usually only lasts a few months and requires multiple applications that may not be so environmentally friendly. 
• Paint any exposed bare wood around your home, including the sides and backs of the materials wherever possible. They will always prefer to tunnel into bare wood vs. painted wood. 

So at the end of the day, whether you decide that for you these guys are friend or foe, now you know a little more about their crazy anxiety-provoking dance. :)