Carpenter bees, often mistaken for bumblebees, are native pollinators recognized for their wood-boring nesting habits. While their penchant for tunneling into wooden structures sometimes earns them a bad reputation, understanding their dietary needs and feeding habits reveals their vital role in the ecosystem. This article delves into the carpenter bee diet, addressing common misconceptions and providing insights into their foraging behavior.
What Carpenter Bees Eat: Nectar and Pollen
Carpenter bees are herbivores, with adults primarily consuming nectar and pollen from a variety of flowering plants. Contrary to common misconceptions, they do not eat wood. Their attraction to wood stems solely from their nesting behavior.
Nectar: The Primary Energy Source
Nectar is the main food source for carpenter bees, offering the energy needed for flight, foraging, and daily activities. Carpenter bees are known to visit a wide range of flowers to collect nectar. They prefer tubular or trumpet-shaped flowers because their long proboscis allows them easy access to the nectar.
Pollen: Essential Protein and Nutrients
While nectar provides energy, pollen is crucial for providing essential proteins and nutrients. As carpenter bees forage for nectar, they inadvertently gather pollen on their bodies, which aids in the pollination of various plant species. Studies of carpenter bees in eastern North America have found the bees’ primary pollen sources are clover and rose. Sunflowers are another popular plant that carpenter bees will frequent in their search for pollen and nectar.
Bee Bread for Larvae
Carpenter bee larvae eat regurgitated nectar and pollen called bee bread. The female carpenter bee stocks the end of the tunnel with bee bread, which is a combination of flower pollen and nectar. She lays a single egg on the food mass, then seals the cavity, or brood cell, with a mixture of wood pulp and saliva.
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Carpenter Bee Foraging Behavior
Adult carpenter bees emerge in early spring, usually around mid-March in Kentucky. The males emerge first and begin patrolling likely nesting spots for females. The males are usually the ones that you see hovering in one spot near large wooden structures, like our barn. The adult females will emerge a few days after the males. They’ll mate and then begin the nesting process. Although the males will forage for their own food, the females are left to gather all the pollen and nectar they need to stay alive and to feed their young. Because of this, the females are most often found foraging on flowers and zipping back to their nests.
By midsummer, most of the adults who emerged in the spring will have died. From the time an egg is laid until the pupa metamorphosizes into a new adult carpenter bee is approximately two months. The new adult bees will hang out in the nest for a few weeks where they finish consuming the pollen and nectar stores left by their mother. In late fall, they’ll return to their nesting chambers to overwinter.
Addressing Common Misconceptions
Several misconceptions surround the dietary habits of carpenter bees. Clarifying these misunderstandings is essential to understanding their behavior and managing their presence around homes.
Do Carpenter Bees Eat Wood?
Carpenter bees do not eat wood as a food source. Instead, they excavate wood for nesting purposes. Female carpenter bees have strong mandibles that they use to excavate tunnels and galleries inside wood for the purpose of creating nests. These galleries serve as a place to lay their eggs and protect their developing brood. The wood shavings created during this excavation process are typically discarded outside the nest.
Do Carpenter Bees Eat Cedar?
Carpenter bees can tunnel into cedar wood, similar to other types of wood. While they may have preferences for certain types of wood, they are not exclusive to cedar. Cedar wood is often used in construction and landscaping due to its natural resistance to decay and insect infestation, but it is not immune to carpenter bee infestations. Carpenter bees can still burrow into cedar if they find it suitable for nesting.
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Do Carpenter Bees Eat Pressure-Treated Wood?
Carpenter bees can also infest pressure-treated wood. Pressure-treated wood is wood that has been chemically treated to resist decay and insect damage. While it is more resistant to insects and rot compared to untreated wood, it is not entirely impervious to carpenter bee activity.
Do Carpenter Bees Eat Painted Wood?
Painting or staining wood surfaces can act as a deterrent to carpenter bees, but it may not always completely stop them from infesting the wood. Carpenter bees are less likely to infest wood that has been painted or stained. The coating creates a barrier that can make it more challenging for them to bore into the wood. The odor and taste of the paint or stain may also discourage them from nesting.
Can Carpenter Bees Eat Through Caulk?
Carpenter bees are not typically known for chewing through caulk. Caulk is a sealant material used to fill gaps and cracks in various surfaces, including wood. It creates a barrier that can deter insects like carpenter bees from entering or nesting in those gaps.
The Role of Carpenter Bees in Pollination
Carpenter bees are important pollinators of many flowering plants found in our gardens, natural areas, and on farms. In fact, 15% of our agricultural crops are pollinated by native bees such as carpenter bees. The eastern carpenter bee is the primary pollinator of purple passionflower (Passiflora incarnata). The purple passionflower produces nectar near the center of its flower. Many different insects, including other species of bees, are able to access and drink the nectar. But those other insects do little to nothing in the way of pollination for the purple passionflower. That’s because the design of the flower is specifically set up for carpenter bees. The purple passionflower’s reproductive parts are located on the stalk that sticks up out of the center of the flower. Both the anthers (male parts) and the stigmas (female parts) are positioned at exactly “carpenter bee height” above the flower petals. So, any carpenter bees that are drinking nectar from the center of the flower can’t avoid coming in contact with them. Dipping under an anther results in getting a good brushing of pollen coating their backs.
Carpenter bees are fantastic pollinators, and they have a unique way of gathering pollen from flowering plants. Buzz pollination, or sonication, is a technique employed by carpenter bees, but also bumble bees, stingless bees, and many others to release pollen grains from certain species of plants. The Best Bees Company Co-Founder Dr. Noah Wilson-Rich notes that these plants have what are known as poricidal anthers, which when vibrated release pollen through small pores; these plants depend on buzz pollination because there is not enough power in the wind or typical bee pollination to extract the pollen.
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Managing Carpenter Bees Around Homes
While carpenter bees are essential pollinators, their nesting habits can sometimes lead to conflicts with homeowners. Here are some strategies for managing carpenter bees around homes:
Prevention
The best management strategy is prevention. Carpenter bees are abundant throughout the eastern United States and they are particularly attracted to nesting in pine and cedar lumber. Applying paint or stain to wood surfaces deters bees from constructing a new nest. An annual springtime application of almond oil over wood surfaces is an excellent deterrent for those who prefer a natural wood finish. These surface treatments make the wood unattractive to the carpenter bee.
Providing Alternative Nesting Options
In addition to reducing the appeal of the wood structures around the home, providing alternative nesting options in the backyard can help further reduce the chances of negative bee-human interactions while providing suitable habitat for these native pollinators. Untreated pine or cedar can be used to lure female carpenter bees away from wooden structures - and it can be arranged as simply or elaborately as desired.
Treatment and Repair
The best times to treat and repair damaged wood and minimize the killing of these pollinators would be late summer (after the summer emergence and before hibernation) or early spring before nest building begins. Wasp, hornet, and bee aerosol formulations sprayed into the holes are effective. Apply the aerosol material into the tunnel entrances and along exposed surfaces. There are also insecticide dust formulations labeled for carpenter bee control. Dust is effective when small amounts are puffed into the tunnel.
A week after treating the tunnels, the carpenter bees should be inactive, and wood can be caulked and repainted. Tunnels must be pre-treated with a pesticide before caulking or the bees will chew through the plugs and reemerge. If you choose to apply pesticide while the bees are active, wait until the female leaves the nest before application.