Carpenter bees

Identification

• Color Yellow and shiny black
• Size 12 to 25 mm in length
• Also known as Xylocope
• Description Carpenter bees are a group of bees that, as their name suggests, build tunnels and nest in wood. They represent some of the approximately 800 species of bees found in Canada. Unlike other social bee species, carpenter bees are solitary creatures that nest in excavated wooden galleries rather than forming large colonies. Named for their carpentry abilities, bees dig through wood to build tunnels with individually compartmentalized cells for their young. Over time, carpenter bees' wood-boring activities can cause severe structural damage. Although carpenter bees can be destructive, they are important pollinators that rarely pose a threat to the physical well-being of humans.

How to recognize carpenter bees

While the eastern carpenter bee's abdomen appears shiny and black, the thorax is yellow and fuzzy. Eastern carpenter bees range in size from 19 to 25 mm in length, and males and females vary slightly in appearance. Males have a yellow patch on their face, while females have a solid black face. Additionally, female eastern carpenter bees have a stinger, while males do not. Being non-aggressive creatures, female carpenter bees only sting when seriously provoked or touched.

Signs of infection

Male eastern carpenter bees often circle around nest openings. Although the insects may appear aggressive towards humans, bees generally defend themselves from other insects and show little concern for humans. However, finding large bees lingering around wooden structures is a sign of carpenter bee activity or infestation. Additionally, homeowners may notice accumulations of shredded wood on the ground below nest entrances.

How to Prevent a Carpenter Bee Invasion

Like most bee species, eastern carpenter bees are ecologically important. Although pest control professionals can be called in to combat pesticide infestations, killing bees is strongly discouraged. Instead, homeowners should consider painting or varnishing exterior wood to repel carpenter bees, as the insects prefer unfinished wood surfaces. Another useful strategy for controlling eastern carpenter bees involves intentionally placing slabs of wood, which are ideal for burrowing, away from the home to provide the insects with a more suitable nesting option than home structures.

Habitat, diet and life cycle

Habitat

Eastern carpenter bees create nests by burrowing into wooden doors, window sills, roof eaves, tiles, railings, telephone poles, wooden garden furniture, decks, bridges or any wood over 50mm thick that provides suitable space for the bees. Eastern carpenter bees have a preference for softwood and are primarily associated with forests in the United States and Canada. Bees also prefer surfaces without paint or varnish. Excavated galleries average 10 to 15 cm in length, but can reach three meters in length with repeated use and when several females are nesting at the same time.

Diet

Unlike termites, eastern carpenter bees do not eat wood by digging tunnels. Instead, adults survive on nectar from many different flowers. Although insects help pollinate many types of flowers, eastern carpenter bees often bore into the bases of flowers and steal nutrients without pollinating them. Developing carpenter bees obtain nutrients from “breadbread,” which consists of pollen and nectar regurgitated by females.

Life cycle

Adult males and females overwinter in wooden tunnels and emerge in the spring to mate. Having made new space for eggs in existing burrows, females stock the chambers with beebread, lay an egg, and seal each chamber. Eastern carpenter bees typically produce six to eight eggs at a time. The insect spends on average 2 days in the egg, 15 days in the larva, 4 days in the prepupa stage and 15 days in the pupa stage. The adults emerge in August, feed, and then return to the same tunnel to overwinter and the process begins again. In general, bees can live up to three years.

F.A.Q.

Why do I need carpenter bees?

Instead of forming colonies with other members of the same species, carpenter bees build individual nests in wooden structures. They build nests in trees and also create artificial objects from wood. Carpenter bees prefer to nest in softwoods such as cedar, cypress, fir, pine, coastal redwood and spruce and prefer to attack exposed, weathered and unpainted wood. Pests invade wood structures such as decks and porches, doors, fence posts, eaves and shingles, patio furniture, railings, telephone poles and window sills.

How concerned should I be about carpenter bees?

The way carpenter bees build their nests can cause both minor and major property damage. When a single carpenter bee drills into a wooden structure to build a nest, the damage is usually minor and limited to cosmetic damage caused by the presence of entry holes. However, if left untreated, future generations of carpenter bees will often reuse the same nests by simply expanding the tunnel network and building new egg cells. Over time, continued expansion of the nest can cause severe structural damage. In addition to damaging property, carpenter bees are an annoyance and nuisance to homeowners. Male bees often defend the nest by aggressively swooping down on intruders. Females can sting, but rarely do so.