That’s not Bob... that builder is a... Bee!? (Carpenter Bees)

This week we are looking at a unique solitary bee that exclusively makes its homes in wood! Carpenter bees are some of the largest bees on the planet, but that's not what makes them so unique. 

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This week's artists: HM Surf, Ghostrifter Official, and S N U G. 

 

Transcript: 

 

Welcome to episode 37 of Insects for Fun! Where we dive into an insect themed topic every Tuesday. This week we’ll be looking at Bear Bees. 

 

Carpenter bees are species of bees within the genus Xylocopa and there are around 500 of them! They often get confused with bumble bees, because both tend to be very large, but a good rule of thumb is that carpenter bees have a shiny bum and by that I mean their abdomen is not usually covered in dense hairs the way bumble bees are. Most carpenter bees are black too, but this is not always the case! Here in Japan we have a really cute carpenter bee known as a Kumabachi which literally translates to bear bee and they can be found hovering still in the air around trees of interest. The thorax on these bees are covered in dense orangey-yellow hairs with a black head and abdomen so when you see them hovering they look like they’re wearing a yellow vest.

 

Carpenter bees can be found worldwide and all of them make burrows in trees or other hard wood surfaces, which can be troublesome if you happen to be in the field of woodworking, but these bees are actually pretty docile and won’t attack you unless you REALLY provoke them (insert mocking cartoon sound). Another thing is that the males don’t have stingers, but this is the case for all male bees and wasps. What’s different though is that male carpenter bees like to patrol an area where a female is nesting, and they will fly up to anything moving within its territory. These bees are all bark and no bite though, so you can simply walk away and they’ll move on. The females have stingers but they’re mostly concerned with making their nesting hole, and won’t be actively chasing you or flying around the same way males are. Now I happen to have a lot of carpenter bees at the high school I teach at in Japan, and I always see the males hovering around in the public garden. I also happen to enjoy the outdoors and walk through that garden, and sometimes I do get dive bombed by male carpenter bees. They straight up stare you down and then zoom at you. I haven’t actually stood still to see if they’ll hit me or not though..

 

Male bees will also have aerial battles which can sometimes result in them tumbling to the ground until one of them finally gives up and flies away. 

 

Carpenter bees are solitary, and as a result they don’t have a hive mentality at all. In fact females oftentimes will be living alone in a small chamber carved out of wood. Sometimes female bees will live in the same shelter, but it's usually not communal. Basically if there is limited availability for housing in a location then multiple female carpenter bees will make holes near each other while still remaining separate. Think of this as like a log motel or something like that where they all have their own rooms or halls if the tree or location has multiple suitable sites. Recent research has actually shown us that sometimes female carpenter bees will work together under the rule of one female, and this head of the house female will not only provide food for her young but also to the other females that are helping her with her nest. This isn’t out of charity though, the bees are simply next in line waiting to take over the nesting site when the head of the house dies or moves on.

 

Now let's talk about what they use for housing along with what the inside of a nest looks like because it's not your average bee home. In the spring female carpenter bees will begin scavenging for wooden structures like benches, railings, sign posts, decks, stumps, logs, basically anything with nice soft wood. This is why the males will be guarding territories they think a female will like. Once a female has mated she begins boring a hole into whatever piece of wood she’s found acceptable. She does this using her strong mandibles, and not long after she creates a near perfect hole, but she doesn’t eat the wood. In fact she leaves the dust behind in a pile, which is how you can be sure it's a carpenter bee and not something else. Once she’s around an inch into the wood she makes a right turn and creates a tubelike gallery stretching down the length of the wood. It is in this tube that she creates walled off cells for individual eggs. Each cell is left with food known as bee bread for when the eggs hatch. This bread is essentially a combination of pollen, nectar and special secretions from the female bee. She has to work her way backwards in order to make walls that separate each individual cell and there can be up to 13 cells per gallery, with the furthest from the entrance hatching first. 

 

Carpenter bees take around 1 month or a little more to fully develop and eggs are typically laid in July, which means you can expect to see new Carpenter bees in August. This is at least the standard case for areas with four seasons, but warmer climates can see carpenter bees all year round. 

 

The adults actually hibernate in new or old homes during the winter and become active once the snow is gone and or the weather gets warm enough for flowers to bloom. Carpenter bees as mentioned earlier do not actually eat wood, and they happen to be good pollinators for shallow flowering plants like sun flowers, eggplant, tomatoes and other fruiting plants. This is due to their short proboscis, but sometimes these bees perform something known as nectar robbing. This happens when a carpenter bee cuts a hole in the side of a flower to steal its nectar without pollinating. You might think this is really bad for the flowers, but it would seem that this act doesn’t actually negatively impact pollination rates. Sometimes it actually encourages smaller bees to crawl into the flower and pollinate it much more directly. 

 

Now some of you might have had experience with carpenter bees, and maybe some of you think these bees will destroy your home or other wooden exteriors the same way a termite will, but the truth is the damage caused by these bees is primarily aesthetic unless you happen to be in area where few natural resources are available and many bees repeatedly use your wooden structures over the years. Wood will naturally rot faster if many holes are bored into it, but there are some things you can do to protect your home or other wooden structures. 

 

Now obviously the best protection happens before a hole is made and you can do this by simply painting the wood or staining it. However if you prefer a more natural look then you could also annually coat your wood with almond oil which is a natural deterrent to the bees. You can also use untreated pine or cedar lumber to lure the female bees away from other nesting sites, and this of course can be set up as simple or elaborate as you want. The bees themselves are not aggressive so if you don’t mind them around and want to support your local native bee community then this is always a nice idea.

 

If you’re in a position where the bees have already started making a home and it poses a threat on infrastructure then you should contact the local authority in pest management.