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In Praise of Carpenter Bees

Carpenter bees are entertaining pollinators that will not sting or bite.

In praise of carpenter bees.

When we were buying our first home, the inspector noted that the ornamental trellis above the back patio was home to several carpenter bees. My immediate fear was this was going to increase the value of the house beyond what we could afford. I knew how much entertainment these harmless acrobats can provide and they were not listed as one of the amenities that came with the sale.  Almost 10 years later, our carpenter bee population has steadily grown. The trellis has more holes in it, but it’s basically doing fine. Best of all, we have never been given a bill for all of the pollination and amusement our carpenter bees have provided for us.

Carpenter bees are closely related to honey bees and bumble bees. However, instead of building hives with a single queen bee and lots of sterile female “worker bees," carpenter bees are not as socially inclined. Unlike honey bees and bumble bees, each female carpenter bee is capable of raising her own family. Here in Pennsylvania, by far the most common of our two species of carpenter bee is Xylocopa virginica. They look like huge black bumblebees and have a shiny black abdomen. The females are capable of stinging, but you would have to work really, really hard to get stung. She will never come after you. Male carpenter bees are less shy around people, partly because they are so focused in protecting their “turf” (and local females) from other male bees. It is very common to see male carpenter bees having aerial “dogfights.” You can easily recognize male carpenter bees by their bright yellow faces. You will never be stung by a male bee (or wasp), since the males do not have stingers. 

Female carpenter bees make new nests by tunneling into wood. They drill their perfectly round 3/8 inch diameter holes by vibrating their strong flight muscles, and slowly turning their bodies around and around.  Their sharp teeth do the drilling, much like a woodworking router. No chewing required! If you look under one of their holes, you might find a pile of sawdust. This is because they do not eat the wood like termites do. The females spend the early summer bringing lots of pollen and nectar to their holes and forming it into little balls, called “bee bread.” This ball of pollen provides a single growing larva with all of the food it needs to grow to adulthood. A female carpenter bee will have about 4-6 larvae, which really isn’t very many for an insect.

The life cycle of carpenter bee starts in the late spring when females lay eggs on the balls of bee bread they busily prepared. During the early part of the summer, the eggs will hatch and the larvae will feed until they become pupae. A few weeks later, a new generation of adults will emerge from their wood holes. Around mid-late summer, the new adults explore the world around them and feed themselves with pollen and nectar (doing some more pollination work). They don’t go very far away from their original holes. If possible, they like to hibernate for the winter in the same holes they were born in. Early in the spring next year, they will crawl out of their holes, ready for action. This is why on one of the very first really warm days of spring, you will be likely to see lots of carpenter bees buzzing around. 

Insecticides and carpenter bees

I know that carpenter bees are a common homeowner complaint. Some people find them a bit scary, which us understandable, especially if they have not been properly introduced to each other. Hopefully, the knowledge that they are not aggressive or dangerous will help more people learn to live with them. Other people are legitimately concerned about the structural damage that can be done to exterior wood on their homes. In these cases, professional assistance may be warranted. If you must remove your carpenter bees, I would definitely recommend against the “do it yourself” approach with household insecticides. In addition to the obvious risks of using toxic chemicals, this can even make your carpenter bee problems worse, as the bees may look for new and even less appropriate places to employ their handiwork. 

With ice cream toppings, “more is better.” This rule does NOT apply to insecticides!  Even when following the instructions, people routinely use insecticides in their gardens at levels that are vastly greater than would be allowable in agriculture!  Of particular concern is a new class of “eco-friendly” insecticides that are available at most home and garden stores. They are called neonicotinoids but are listed on the label with a variety of unpronounceable names (e.g. imidocoloprid).  If you can’t tell if a product contains neonicotinoids, ask the store manager to help you figure it out, or try calling the phone number on the package.

Neonicotinoids are less toxic to humans than many of the “old fashioned” insecticides you might have used in the past. They are artificially synthesized chemical mimics of nicotine, a natural insecticide found in tobacco. Neonicotinoids are taken up into plant fluids including nectar, making the plant itself toxic to insects that feed on them. So far so good, what’s the problem? Unfortunately, they can build up to alarmingly high concentrations in the flowers of some ornamental shrubs and trees. In this way, they can be found in plant nectar in high doses that have proven to be lethal to many pollinators. Some scientists are pinning the blame on these commonly used insecticides for all of the troubles that honeybees have been experiencing (such as colony collapse disorder). This is still an active area of research, and the jury is still out. Meanwhile, solid research into the environmental effects of neonicotinoids used in the home & garden setting is urgently needed.  To what extent are they disrupting the lives of honeybees, native bees and other pollinator insects such as butterflies?

If you are at all inclined to use insecticides in your backyard (after consulting with the fireflies, bees and butterflies who will also be affected), please read this article before heading off to the local hardware store. 

http://www.wired.com/wiredscience/2012/04/neonicotinoids-gardens/#more-106221

If do not have carpenter bees and want them, or you would like to encourage your carpenter bees to nest a little further away from your house, I would suggest putting some weathered, unpainted lumber (like untreated 2X4s) out for them to use as a home.  Place it as near or far away from your house as you please.  For a few dollars and a couple of nails, you can gradually increase the aesthetic and ecological value of your property by building a population of friendly and helpful carpenter bees.

This post is contributed by a community member. The views expressed in this blog are those of the author and do not necessarily reflect those of Patch Media Corporation. Everyone is welcome to submit a post to Patch. If you'd like to post a blog, go here to get started.

Margie Peterson May 23, 2012 at 02:38 PM
Marten Edwards, you're like our own Bill Nye the Science Guy or Carl Sagan for bugs. Thanks for a great read.
Mallory Vough May 23, 2012 at 03:15 PM
So... You're telling me that it's totally unnecessary to run around in circles -- screaming -- in utter fear when a carpenter bee flies in my personal bubble space? Huh. Who knew?! Thanks for sharing! This was quite enlightening!
Anonymous May 23, 2012 at 04:03 PM
It's not that hard to get stung by a female. Just grab the window ledge and make sure one of your fingers covers a hole. Quite painful!
Mark Buckelew May 23, 2012 at 05:03 PM
Another no- insecticide solution for the btunnelling I found inadvertantly is that a coat of paint or opaque stain inhibits the bees. No more holes on the painted portions of our deck but they still like the underside which is not painted. As long as the paint is low VOC you can stay more or less environmentally friendly too.
Brooklands May 23, 2012 at 05:37 PM
We had bees tunneling in the painted trim wood around our entrance door to a wood sided park model camper. The exterior trim paint did not stop their work at all.
Cynthia May 23, 2012 at 08:28 PM
I wondered what those big black bumblebees were! Now I know! Thanks! Nice article!
Awww SNAP!shots - Nancy Nadolski May 23, 2012 at 08:44 PM
Mallory...I'd keep runnin' if I were you...my old mailman was stung by one exiting his shed and said it felt like somebody smacked him in the forehead with a baseball bat. We find a good badminton racket is a nice deterrent to carpenter bees too...Makes a nice PING sound when you whack one....
Mallory Vough May 23, 2012 at 09:00 PM
Oh my goodness, Nancy! I haven't laughed that hard in a long time. I swear I just snorted.
Andrew Wilt May 23, 2012 at 09:33 PM
Nancy, a badminton racket works splendidly for this purpose, especially if you hit them right in the middle of the racket! Two years ago I sent 127 of the little buggers to the great beyond, last year was 110, and this year is 69 so far. I think their numbers are faltering. I know my ragged old porch is!
Arthur Joel Katz May 23, 2012 at 09:47 PM
Buzz and Bravo. Anyone like Andy Wilt who keeps count on the number of Carpenter Bees he has killed probably is a member of the NRA. Absolutely wonderful column. Thank you very much.
Valerie McCracken May 23, 2012 at 10:15 PM
Educational, uplifting and fun! Thanks for your great insights. Once afraid of these little creatures, I am not interested!
Mark Jamison May 23, 2012 at 11:55 PM
Killing carpenter bees with a tennis racket and keeping count over the years....another individual completely out of touch with with his environment and devoid of any common sense.
Pam Ruch May 24, 2012 at 12:20 AM
Thank you for a sane article on a valuable native pollinator. I wonder if you have similar tolerance for another scary backyard inhabitant -- the Cicada Killer wasp ??
Andrew Wilt May 24, 2012 at 01:26 PM
Mark, I really didn't appreciate your reply. However, mea culpa, there is truth in what you wrote. After some additional reading I realize I never considered that carpenter bees might be pollinators. My concern was and is that they are tunneling through my porch. I will provide them with another location of suitable wood away from the house and leave them alone from now on. As far as counting them goes, I have a touch of OCD, I guess I'll find something else to count.
Marten Edwards May 24, 2012 at 01:32 PM
Stay tuned, its on my short list :)
Peter May 24, 2012 at 05:03 PM
i built a trap...wood box with a couple 3/8 holes in it and an empty plastic water bottle at the bottom. at the end of the day when they're looking for holes to crawl into, they go into the box and fall into the bottle. i'm not being mean, it's just that our deck was home to approx. 30 of them and they made the deck unusable as they constantly dive-bombed my head.
Mark Jamison May 24, 2012 at 05:27 PM
I apologize Andrew. I was too harsh. I have become very sensitive to issues like this as I grow older. Like so many of my generation, I was taught to shoot, spray, or beat with a stick ( or racket) anything that was irritating, ugly, or in any way inconvenient. I have since come to realize that we are all in this together and although we may not recognize something's purpose in this web we can be damn sure it has one. And as we watch Monsanto singlehandedly destroy the American honeybee through the use of GMO's we must realize that all the other pollinators become all that much more important. And if it's any comfort, I have a wooden barn that was built during the civil war. It's riddled with bee holes. It was here long before me. It will be here long after I'm gone.
Mark Jamison May 24, 2012 at 05:29 PM
I give up......
Andrew Wilt May 24, 2012 at 05:45 PM
Mark, thank you. No problem! And don't give up!
Jimmy Madden May 25, 2012 at 02:17 AM
Marten, thank you for the very informative article on the carpenter bee. Easton Patch users...Thank you for the awesomely funny and disturbing comments left in trace of this article. I am not sure what was better
Karen Samuels May 25, 2012 at 02:13 PM
Not Andy! He is a peaceful man.

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