Yes, a specific type of bee does chew through wood, though the majority of bee species are beneficial pollinators that do not cause structural damage. The question of wood-boring comes down to one major family of insects that utilizes wooden structures for nesting, rather than for food. This activity can become a significant concern for homeowners as it compromises the integrity and appearance of lumber over time.
Identifying the Wood-Boring Bees
The primary culprits behind this wood-chewing activity are the large, solitary insects known as carpenter bees, specifically species within the genus Xylocopa. These insects are frequently mistaken for their close relatives, the bumble bees, due to their similar size and coloration. The simplest way to distinguish between them is to observe the abdomen. Bumble bees are covered in dense, fuzzy hair across their entire bodies, including their abdomens, giving them a plush appearance. Carpenter bees, in contrast, have a smooth, shiny, black abdomen that appears hairless and almost metallic. They often have a bright yellow, fuzzy thorax, which contributes to the confusion. Unlike social bees, carpenter bees do not live in large colonies or hives; instead, the female works alone to excavate a nest.
The Mechanics of Tunnel Excavation
Female carpenter bees bore into wood to create nesting galleries, not to consume the material as food. The wood shavings, or frass, that result from this excavation process are often visible outside the hole, resembling fine sawdust. The entrance hole itself is a perfectly circular opening, typically about one-half inch in diameter, just large enough for the bee to enter. This initial bore penetrates the wood for about half an inch to an inch across the grain. At that depth, the bee abruptly changes direction and excavates a tunnel parallel to the wood grain, which can extend six to eight inches in a single season. The purpose of this tunnel system is purely reproductive: the female constructs individual cells within the gallery, provisions each with a ball of pollen and nectar, and lays a single egg. Over several years, these galleries are often enlarged or reused by successive generations, which can lead to extensive tunneling up to ten feet long within a single piece of lumber.
Protecting Structures from Nesting Activity
The best defense against carpenter bee activity is to make wooden structures unappealing to them, as they strongly prefer bare, unpainted, or weathered softwoods like pine, cedar, and cypress. Applying a fresh coat of paint, varnish, or quality sealant acts as a physical barrier that discourages the female from attempting to bore into the surface. Regular maintenance and inspection of fascia boards, deck railings, and soffits, where they commonly nest, can prevent initial entry. If an infestation is already present, direct treatment of the tunnels is necessary to manage the population. Insecticide dusts or sprays labeled for wood-boring insects should be applied directly into the existing holes, ideally in the evening when the bees are less active and likely inside. After confirming that the bees have vacated or are no longer active, the holes must be sealed to prevent future generations from re-using or expanding the galleries. Sealing can be accomplished by plugging the holes with wood putty, a wooden dowel, or steel wool, followed by painting the repaired surface. This combination of chemical treatment and physical sealing is important, as carpenter bees are highly attracted to old tunnels for nesting.