How to get rid of wood bees?

19.06.2020. 14:00

Wood bees, also known as carpenter bees, are a special kind of bees who got their name from their nesting behavior, burrowing into hard plant material such as bamboo or wood. 

Carpenter bees are part of the Xylocopa genus, which includes about 500 types of bees. These bees are often confused with bumblebees because of physical similarities. If you notice large black bees hovering around your house, it's most likely a carpenter bee. 

The wood boring bees can be destructive, but there are ways to manage it. They are an essential nature's asset because of their job in a grand scheme of things; they are incredible pollinators. 

How to identify carpenter bees?

Since they bore into wood, carpenter bees are known as wood boring bees. Carpenter bees are similar to bumblebees in both appearance and size. 

Both bumblebees and carpenter bees are large, with black and yellow patterns. An easy way to tell them apart is by looking at their abdomen. Bumblebees have an abdomen covered with dense hair, while carpenter bees have a shiny abdomen. 

The big difference between them is also their way of life; carpenter bees are not social insects. Carpenter bees are solitary bees that do not form colonies, while bumblebees live in colonies of 50 - 400 bees

Life Cycle

As we mentioned, wood bees are solitary bees. But there are exceptions to this rule; some species have simple nests where mothers and daughters cohabit. In such nests, there is a division of labor. Either multiple females forage and lay eggs, or one female does those things, and others guard the nest. 

The individual adult bees often live in previously constructed brood tunnels and those bees that survive the winter mate the following spring. After fertilization, female wood bees excavate a tunnel in wood to lay their eggs. A bee makes a tunnel in the wood using its mandibles while also vibrating its body. 

Even though it might seem so, wood-boring bees don't eat wood. The leftover bits of wood are discarded or used to build partitions between cells. The entrance hole is usually perfectly round with the diameter of your little finger. Below the opening, you might notice coarse sawdust, and you might hear tunneling sounds within the wood. 

After burrowing the wood for a short distance, a bee continues tunneling at the right angle, parallel to the wood surface. Then a bee constructs five or six cells inside the tunnel with the purpose of individual housing eggs. 

Carpenter bee eggs are enormous when we compare it to the size of the female carpenter bee, so it's not a surprise that carpenter bee eggs are considered some of the giant eggs among insects. Each cell is filled with one egg and some pollen and then sealed with regurgitated wood pulp. 

Hatching and maturation take several weeks, and during that time, pollen serves as a food for the developing larvae. In the late summer, the new generation of adult carpenter bees emerges for forage. They return to the wood in fall because of hibernation.   

When it comes to mating, we can identify two different mating systems, which can be determined by examining male bees. Species in which males have large eyes have a mating system characterized by males searching for females to pursue. 

The other system is characterized by males with small heads and large hypertrophied glandular reservoirs in mesosoma, releasing pheromones into the air behind the male. These pheromones signal the female bee that a male bee is present. 

Wood boring bees a sign of trouble?

The preferred nesting spots are softwoods such as pine, spruce, cedar, and cypress. Usually, they attack exposed unpainted wood. 

When chosen wood structures are doors, decks, porches, roof eaves, or any other wooden part of your house, that is when problems arise. If you are having an issue with only a few bees, then the damage might be minor. In this case, you will usually have cosmetic damage because of the entrance hole's presence. 

However, each new generation of bees will make the tunnels deeper and more branched out, increasing the structure's damage. Moreover, holes in the wood can also promote rot and decay. 

Signs of infestation

A clear sign that you might be dealing with an infestation is male bees hovering around the nest opening. They might seem aggressive, but they usually only guard against other insects. Another sign that you might be dealing with a carpenter bee infestation is the accumulation of pulverized wood bellow the nest entrance. 

Another point we need to make about male wood bees is that they are harmless since they don't have a stinger. Female wood bees can sting, but they do it only if handled or provoked. In general, carpenter bees are less likely to sting than social bees and wasps. You can read more about it here

How to get rid of wood bees with chemicals?

The first step to removing wood bees is to locate the wood where the bees are active and apply insecticidal dust into nest openings. The best way to do it is to puff the dust up into the tunnel, so the dust coats all sides. We advise you to do this at night to avoid possible stings. 

A flashlight is necessary for work at night, and there is a trick to prevent triggering the bees. Bees cannot see the red light so you can tape a piece of red cellophane over the flashlight. Doing this will enable you to see the openings, but the bees won't be agitated. We also recommend wearing protective clothing, goggles, gloves, and a dust mask. 

To prevent spreading the insecticidal dust everywhere after you are done, launder any contaminated clothing (don't mix them with other laundry items) and take a shower. Since this task brings some risks, one option may be contacting your local pest control who will manage the infestation safely. 

One thing to remember is not to plug the holes immediately because wood bees should be able to go through the openings to get in contact with the dust. For a complete solution of an infestation problem, this process should be done three times throughout the year

The first treatment should be done in the spring, then in mid-summer, and lastly, in early fall. To prevent new bees from making the leftover tunnels into their home, plug the holes with wood putty or wooden dowels. Moreover, it would be good to paint or varnish the entire wood surface to make it less likely for carpenter bees to build new nests. 

We have to mention that using chemicals to get rid of wood bees should only be done as a last resort. If you don't have a big problem with wood boring bees, we recommend trying organic solutions which may solve your problem without hurting the bees. 

Natural ways to manage an infestation

Bee houses

Bee houses are usually made of wood, paper, or bamboo tubes housed in a small frame, so they are quite attractive to solitary bees such as carpenter bees. 

There is no guarantee that placing these hotels will completely prevent carpenter bees from attacking other wood surfaces, but it can help in reducing the damage they can do. 

Here you can check some of our favorite bee houses if you are interested in this method of managing an infestation.

Citrus oil

Citrus oil is a natural carpenter bee repellent that you can easily make yourself. 

To make this oil, you need to boil peels from a variety of citrus fruits in water and then let it simmer for 10 minutes on reduced heat. When it's done, let it cool off and pour the water into the spray bottle. Of course, you need to strain the peels from the water before pouring it in. 

Apply this spray on the nest and reapply until all female drone bees have relocated. When you are sure that the nest is empty, fill out the holes, and paint the wood.

Paint the exposed wood

Once carpenter bees start to their destructive burrowing, it can be quite hard to manage it. Thus, we believe it's easier to be proactive in discouraging the bees from burrowing where we don't want them to. 

Paint all exposed surfaces with a primer and two coats of exterior paint. Wood stains and varnishes can offer some protection, but they are less effective than paint. 

Hang a decoy wasp nest

Wood bees naturally avoid nesting in the same area as wasps, so this tactic may encourage the bees to prevent making nests close to the decoy nest.  

Making a decoy wasp nest is quite easy and doesn't require much material. Just stuff a brown paper bag with lightweight material such as paper, moss, or plastic bags. Tie off the open end and hang the bag in the area you want to protect. 

With this method, you should keep in mind that this only deters the bees from building new nests, it won't scare away the bees who already built nests in the area.

Carpenter bees can be a nuisance, but they are more than their nesting habits

Many people consider carpenter bees a nuisance because they tend to burrow into wood. However, these bees are important pollinators. 

There are over 500 species of carpenter bees, and each of them is essential for its environment. Carpenter bees have short mouthparts, so they are crucial pollinators of shallow flowers. 

For example, the only pollinators of passion flowers are carpenter bees. Their pollination is contributing a food source for wildlife, which encourages a stable ecosystem.

Do you have any experience with carpenter bees?