How to Get Rid of Carpenter Bees
Carpenter bees are a large solitary bee. They resemble a bumble bee, but their behaviors couldn’t be more different. Carpenter bees derived their name from their practice of boring holes in wood and excavating the wood to shield their eggs and developing young. Carpenter bees exhibit some intriguing traits. However, if carpenter bees are boring into the siding of your home, underneath the soffits, or causing your fence or deck to loose structural integrity, you may be less inclined to appreciate their finer characteristics. Despite their voracious reputation, carpenter bees do not eat wood for nourishment and nutrition. Like other bees, carpenter bees eat pollen and nectar from the flowers that they help to pollinate. Most of the time, carpenter bees and humans peaceably co-exist, but in some situations carpenter bees make pests of themselves and must be dealt with. Join us in this article as we explore an often misunderstood and mysterious insect.
Identifying Carpenter Bees
Carpenter bees visually look very similar to bumble bees. Often when people complain of bumblebees hovering under the eaves of their home, they are actually observing the male carpenter bee. Adult Eastern carpenter bees are between 0.75” to 1” in length. Like bumblebees, they are splashed with black and yellow patches. The thorax, or middle section, of carpenter bees is fuzzy yellow, and the abdomen, or hind section, is shiny and black. Female carpenter bees have a black face, whereas male carpenter bees have a yellow face. The easiest way to distinguish carpenter bees from bumblebees is to remember that carpenter bees have a shiny black abdomen and bumblebees have a much fuzzier or hairier abdomen.
The subfamily of carpenter bees is actually divided into 2 genera, Ceratina, or small carpenter bee, and Xylocopa, or large carpenter bee. Xylocopa comes from the Greek for wood cutter. The small carpenter bees excavate stems of some shrubs and small bushes, where large carpenter bees use large stumps, logs, or solid pieces of wood to house their young. For purposes of this article, we will focus on the large carpenter bee since bees of this genus are the ones that attack our homes, fences, and decks.
There are many distinct species of large carpenter bees in the United States. They inhabit a range of ecosystems and can thrive in different climates. In the United States carpenter bees can be found from Florida to Arizona and north to New York. Carpenter bees are especially pesky in the northeast where wood siding on homes is more common.
Carpenter Bee Stings
Carpenter bees do not have the aggressive reputation of yellow jackets or hornets. In fact, only female carpenter bees have the ability to sting. In reality though, the female carpenter bee is more interested in building her nest and setting her progeny up for success, than stinging a human who happens to walk by. However, if captured and contained in your hand, excruciatingly harassed, or if you are attempting to apply pesticide to her domain, the female carpenter bee can and will exact her revenge in a sharp painful sting. Unlike honeybees which have barbed stingers, carpenter bees have smooth stingers. Therefore, they can sting their adversary multiple times; however, once they lose their stinger they will die.
Female carpenter bees are often described in the literature as docile, while the males are described as territorial and more aggressive. However, the male carpenter bees lack the ability to follow through on his threats. On stinging insects, the stingers are modified ovipositors; therefore, only female bees, wasps, and ants technically sting. The male carpenter bee does not possess a stinger, but he does not let that quell his protective instincts. While the female carpenter bee is busy preparing her nest, laying eggs, and provisioning for them, he aggressively flies about the entrance to the nest. The male assertively patrols the area, loudly buzzing about, and may even dive bomb and pretend to sting potential intruders. Most people don’t stick around to closely examine his equipment and color patterns and assume you have stumbled upon an aggressive stinging colony.
Behaviors and Life Cycle of Carpenter Bees
Conjuring up visions of bees, usually brings to mind hundreds or thousands of bees swarming around a buzzing hive. The social nature of honeybees and bumblebees is closely associated with our cautious approach to handling bees and our innate fear of them. Carpenter bees are unusual though, they are considered one of the species of solitary bees. They do not aggregate in large numbers and divide up work. Drones and workers do not serve a solitary queen. Rather, the female carpenter bee lives a life of isolation; a life spent in service to her children, and then she dies.
To begin her nest the mated female carpenter bee locates a piece of solid wood suitable for her purpose. Many times, carpenter bees may return to the nest from which they emerged, or locate another nest used by previous generations. Carpenter bees utilize dead, but solid, not decaying or crumbling wood, such as fence timbers, decks, overhangs, wood shingle siding often found on the side of houses, and any other exposed wood. A common access point for carpenter bees is coming through the back face of the trim under the eaves of your home. This area is usually not painted, and provides the ideal nesting location.
They almost always attack from the underside of the wood and use their strong jaws to chew into this strong hard wood. If you are in the area and listen closely, you can hear the drilling out of the wood. Carpenter bees excavate nearly a perfect circle which is ½” in diameter. No other wood boring insect makes a hole this perfectly round or as large. As they enter the wood, they commonly leave a pile of sawdust beneath the surface of the hole. Once they have chewed their way into the wood about 1” deep, they make a hard right or left turn and begin chewing at a right angle with the grain of the wood.
As they work their way through the wood, carpenter bees do not eat the wood for nutrition like termites. Rather, they kick the decimated saw dust out of the nest. This nest construction typically begins in mid-May. The excavated nest gallery usually extends 6-7” from the circular entrance hole, but sometimes they can be as long as 1 foot long. Occasionally, carpenter bees start their nest using a previous gallery. In these instances, they tend to extend the original nest. Despite their solitary nature, sometimes, more than one carpenter bee will use the same entrance hole on the piece of wood. However, from there, they branch off and form their own gallery or nursery. It is in these pieces of wood with multiple carpenter bees in them, that carpenter bees transcend from being an annoying menace and become a pest.
As carpenter bees excavate their nests, they have their children on their minds. Carpenter bees collect pollen and nectar and turn it into a substance called bee bread. This bee bread will sustain the immature carpenter bees after they hatch. The mamma carpenter bee carefully prepares a vault for each of her eggs as she will not be with them when they hatch. Generally, each carpenter bee nesting gallery contains 6 or 7 vaults, each containing an egg and enough bee bread to support the hatchling through the larval and pupal phase of its metamorphosis. The carpenter bee lays an egg next to the ball of pollen and nectar then places a door on the vault with chewed up wood pulp. This wooden partition material she creates is similar to particle board. She continues down the gallery, filling the tunnel with cavities each containing 1 egg and 1 ball of bee bread/pollen/nectar. She seals each individual cavity leaving their entire maturation process to nature.
Depending upon temperature and other circumstances, carpenter bees can go from eggs to adults in as little as 1 month. When the eggs hatch, the larvae consume the ball of nectar and pollen left for them in their cell. After the larvae consumes the bee bread it enters the pupal phase, during which it transforms into an adult. As adults, they must chew their way out of their cell and nest. Miraculously, even this process is controlled by the laws of nature. The last egg laid, which is the closest to the entrance of the nest is the first one to hatch and escape the nest. The carpenter bees proceed to hatch in falling domino fashion until the first egg laid is the last one to hatch. In this manner, each carpenter bee can safely escape its vault. Newly developed carpenter bees usually emerge in August, feed on nectar and pollen for a while, then overwinter/hibernate in their nest. The initial mother carpenter bee dies within weeks of completing her egg vault.
The absoluteness of the solitary nature of some species of carpenter bees is somewhat being called into question. In warm climates, some species of carpenter bees can produce 2 or 3 generations per year. In these situations where 2 or 3 broods are sired per year, biologists and entomologists have peeked into the nests using x-ray and other imaging technology. What they observed forced some entomologists to admit that some carpenter bees can be primitively social. Scientists observed newly hatched adults to temporarily nest with their mother. They also observed foraging carpenter bees returning to the nest to feed the bees that remained in the nest. This shocking behavior is believed to be extremely limited, but nonetheless, reminds us to continue the pursuit of further knowledge.
Damage Caused by Carpenter Bees
When weighed against termites for their ability to damage homes and personal property, carpenter bees are a minor inconvenience. Carpenter bees are not the culprit when buildings are condemned and rarely cause expensive damage. However, if allowed to continually excavate in certain areas, the wood can degrade and lose its structural integrity. This generally does not happen with one bee in one season. Carpenter bees do like to come back to the same area from which they emerged. Over the years, this may lead to many carpenter bees hollowing out a particular fence post or patch of siding on your home. The compounded effect of a large number of carpenter bees over successive years working a particular piece of wood may cause structural and aesthetic harm to your home.
Another common complaint associated with carpenter bees is their unsightly habit of releasing their excrement just before entering their hole. In a fan-shaped pattern, yellowish-brown excrement begins to stain the area below the carpenter bee entrance hole. This streaked defecation on a wall or deck may begin to hold dirt, mold, and other unsightly and unsanitary substances. As described above, it is especially frustrating if there are many carpenter bees near the same area. Season after season, scrubbing carpenter bee waste from the surface of your home is no one’s idea of a great Saturday afternoon.
Woodpeckers can recognize carpenter bee infested wood faster than most people. When woodpeckers notice the ½” perfectly round circle, they know tasty carpenter bee larvae, pupae, or perhaps even bee bread may be on the menu. Woodpeckers can cause more damage to your home faster than carpenter bees ever will. The holes left behind from a woodpecker are bigger and much more obvious than a carpenter bee hole. Thin wood, such as the siding on a home, is easily broken by woodpeckers searching for the meal in the encapsulated cavities. After their feast, they leave holes which allow rainwater and other sources of moisture to enter. Moisture in a home always leads to successive problems such as wood decay fungi, mold, and other insect infestations. These large woodpecker holes may also permit nuisance wildlife such as racoons, squirrels, or rats/mice to take up residence inside your home.
Carpenter Bees as Pollinators
By this time, nearly everyone has seen the public service announcements educating on the benefits of bees. Without bees our food supply would dwindle and countless among us would starve. While honeybees and bumblebees get most of the love and respect from these promotions, carpenter bees deserve pollination recognition as well. Carpenter bees have short mouthparts and are important pollinators of many open-faced or shallow flowers such as bee balm, asters, daylilies, salvia, lavender, and zinnia. Carpenter bees pollinate passion fruit flowers, eggplant, tomatoes, and many other fruits and vegetables.
Carpenter bees pollinate using a technique called buzz pollination. Carpenter bees prefer to eat in the early morning hours. Once the bee lands on the flower, they use their powerful thoracic flight muscles to quickly vibrate the flower causing the pollen to release out of the anther. This pollen shakedown is highly effective for the flowers that are accessible. In their less earth friendly moments, carpenter bees are nectar robbers; they split the tube of a flower and steal nectar without having pollinated the plant. At any rate, they are important pollinators, docile and non-aggressive, that should be permitted to live and propagate if possible.
Signs of Carpenter Bee Infestations
From past experience, if you know that your home is prone to carpenter bee invasion, there are a few things that you can do. Especially, if the same area is bombarded every single year, the carpenter bee activity may be degrading the structure of infested area. You can use the carpenter bee’s biology and habits to help you locate new nests. Recall that the male carpenter bees patrol the area and attempt to bully people, animals, and other bees away from the area where the female is busy preparing the den for her eggs. If you are walking the perimeter of your home and hear a loud buzzing and see and feel aggressive dive bomb maneuvers, you are probably in the vicinity of a budding new carpenter bee nest.
Anywhere you suspect carpenter bee activity, inspect closely for the tell-tale signs. Usually on the underside of the wood, you will find a perfectly circular ½” hole. Underneath that hole, you may find a pile of saw dust on the ground. Adjacent to the hole you may find brownish-yellow fecal matter sprayed along the wall. To determine the breadth of the infestation carefully inspect the area for signs of additional nesting locations. Once you know the severity of the infestation, assess whether the carpenter bee poses danger to the integrity of your home. Recall that woodpeckers and carpenter bees often come in pairs. Aesthetic considerations are valid to consider here as well. The risk of being stung by a carpenter bee is low, but if you know you have a particularly inquisitive child, take that risk into consideration as well. If you determine that the carpenter bees should be treated as a pest, there are pest control measures that can effectively deal with these nests and prevent the young therein from emerging.
How to Get Rid of Carpenter Bees
The first line of defense against carpenter bees is to apply a simple varnish or paint on the wood. Although it is not 100% guarantee, they prefer not to nest in wood that is covered with paint or varnish. Oil based paints and polyurethane seem to work the best. Wood stains show the least deterrence against carpenter bees. Although not completely understood, the reason for this is likely the paint or varnish has changed the smell or taste of the wood to warrant it unknown, unsafe, and therefore dangerous. Rather than deal with the dangers of that unfamiliar paint or varnish, carpenter bees would rather find an organic or untreated log, deck, fascia board, or piece of outdoor furniture.
In some cases, homeowners prefer to remove the affected wood, and replace it with pressure treated wood. This is not practical if your home is covered in wood shingles, but for isolated infestations, this may be the easiest and most effective way to get rid of carpenter bees.
Pest Control Treatment for Carpenter Bees
Carpenter bees are best attacked in a specific targeted treatment rather than a general broad approach. While it is tempting to just apply a blanket pesticide spray across your deck, shed, fascia board, wood siding, or any other surface that carpenter bees are inundating, this is not the best solution. First, many liquid insecticides are not labeled for such an overly broad application, and would thus be illegal. Second, this type of blanket treatment would likely have a negative effect on non-target insects, including other beneficial pollinators. Third, to remain even marginally effective, you would have to retreat at least once per month; this would conclude with having far more pesticide on and about your home than is recommended. Fourth, carpenter bees can attack any wood surface on your home. It is impossible and impracticable to attempt to drench every wood surface about your home with pesticide every 30 days. In addition, spraying the protective male carpenter bee hovering about the nest, will really not stop the female from continuing her mission.
As daunting and endless as the task may seem, you will gain greater carpenter bee control by addressing each carpenter bee gallery individually. In the end, this method will require less time, money, and prove to be more effective than a blanket approach. When assessing carpenter bee nests, determine whether this is a do-it-yourself job, or if this is better handled by a licensed and insured pest management professional. Safety considerations are paramount. Carpenter bee nests often involve awkward positioning on ladders and applying pesticides over your head. Although usually docile, if caught up in a cloud of insecticide, the female carpenter bee can and will sting repeatedly. Performing this balancing act outstretched on a ladder may end in a painful tumble.
Insecticides labeled for carpenter bees come in several formulations. Most pest management professionals choose insecticides in the form of a dust or an aerosol spray. Whichever formulation you chose, make sure it is labeled for carpenter bees and that you follow all instructions on the label. Apply the insecticide to the carpenter bee galleries as instructed on the label and then wait. Do not plug the holes immediately! The idea is to ensure that the carpenter bee contacts the insecticide and spreads it throughout her nest including any eggs that may have already been laid.
A few days after the insecticide treatment, the entrance hole to the carpenter bee gallery should be sealed. The insecticide should have killed the carpenter bee, but this particular piece of wood will continue to be susceptible to carpenter bees unless the hole is sealed. Remember, carpenter bees will gladly utilize a nest previously excavated by another bee. You can use a small ball of aluminum foil, caulk, wood putty, or a plastic plug. In conspicuous areas, the hole can be plugged with a wooden dowel, sanded, and painted or varnished to seamlessly integrate.
Some people try to take a short cut and skip the insecticide step, thinking that plugging the hole alone is sufficient to solve the problem. Without insecticide in the hole, adults may emerge from their cavern with the ability to drill themselves out of the nest. The necessary step of applying pesticide to the gallery ensures that this carpenter bee gallery is solved once and for all.
How to Prevent Carpenter Bees
Not all carpenter bees can be prevented, but vigilant inspections and prompt treatments can prevent unsightly damage and structural decay. However, certain conditions around your home invite carpenter bees more than others. By making your home and surrounding outdoor spaces less inviting to carpenter bees you can generally avoid the most devastating of consequences.
Carpenter bees rarely choose to infest painted or varnished wood. Oil based or polyurethane based solutions will best help to prevent carpenter bees. Staining wood does not seem to have the same protective qualities though. If you like the natural wood look, a coat of clear polyurethane will not compromise your look but offer a defense against carpenter bees.
Additionally, by choosing synthetic materials, not made of wood, you can prevent carpenter bee infestations. Carpenter bees will not attack vinyl, aluminum siding, mason, or cement board. By replacing carpenter bee infested wood with composite materials, the carpenter bees cannot reinfest that same item. Keep this in mind when replacing outdoor furniture, porch rails, or banisters. Although this option is expensive, if your area is highly prone to carpenter bee attacks it may be worth the additional expense, particularly if you are in the construction phase. If composite materials are not a viable option, consider pressure treated wood for these at-risk areas.
As stated above, painted surfaces are less attractive to carpenter bees, but by no means immune. By keeping the wood on and around your home in good repair, you may deter some carpenter bees. Carpenter bees can take advantage of a hole that is already started and utilize it for their own purposes. Nail holes and cracks should be filled with caulk or putty before applying paint.
Some areas of the country battle more carpenter bees than others. In ripe conditions, carpenter bees can become quite a nemesis. Our professional team of trained and experienced pest management professionals know where to look for and how to access carpenter bee tunnels. Despite the many fascinating characteristics and their beneficial pollinating impact on the environment, you must take steps to protect your most valuable investment. Spring and summer are prime carpenter bee seasons; call Nextgen Pest Solutions today to protect your home and family from these pesky excavators.