Many organisms that consume wood are social, living in vast, hidden colonies with a strict caste system. They work collectively to break down and feed on cellulose, the primary component of wood, often causing extensive structural damage to buildings from the inside out.
Another major category includes species where the immature larval stage is responsible for the destruction. These young live hidden within the material, tunneling and feeding for years before emerging as adults, leaving behind a network of passages and exit holes.
Some types are particularly drawn to moist or decaying material, as the fungi and moisture help them digest the tough cellulose. They are often found in areas with water damage, rot, or poor ventilation, and their presence can indicate an underlying moisture problem.
A distinct group does not actually consume the material for food but excavates it to create nesting galleries. They remove pieces to build their nests, pushing out a coarse sawdust-like material, and prefer to target softened or weathered surfaces.
Insects That Eat Wood
Termites
Termites are among the most notorious wood-eating insects. They consume cellulose, the main structural component of plant material, and are capable of digesting it with the help of gut microbes. Subterranean termites live in soil and build mud tubes to access wood, while drywood and dampwood termites nest directly inside timber. They cause billions of dollars in structural damage worldwide each year.
Carpenter Ants
Unlike termites, carpenter ants do not consume wood for nutrition; instead, they excavate it to create smooth-walled galleries for nesting. Their colonies expand inside decayed, moist, or hollow wood, weakening trees or wooden structures. Over time, their tunneling can compromise the integrity of lumber.
Powderpost Beetles
Powderpost beetles are small, wood-boring beetles whose larvae feed on dry, seasoned hardwoods. They reduce wood into a fine, flour-like powder as they tunnel through it. Infestations often occur in flooring, furniture, and beams, and are identified by small, round exit holes.
Deathwatch Beetles
These beetles infest hardwoods, particularly oak, that are already decayed or moisture-damaged. Their larvae feed inside wood for years, creating winding tunnels before emerging as adults. The name “deathwatch” comes from the ticking sound they make, once associated with omens.
Old House Borers
Old house borers are longhorn beetles whose larvae feed on softwood timbers, especially pine. They are common in houses less than 100 years old, where structural wood provides a food source. Their feeding leaves behind large oval exit holes and frass (wood dust).
Ambrosia Beetles
Ambrosia beetles bore into trees, but unlike other wood-eaters, they don’t consume the wood directly. Instead, they cultivate a symbiotic fungus (ambrosia fungus) within their tunnels, which they feed on. While not strictly digesting wood, their tunneling damages living and dead trees.
Bark Beetles
Bark beetles infest the inner bark and phloem of trees. While their primary diet is the nutrient-rich cambium rather than solid wood, their tunneling often extends into the outer wood layers. Infestations can girdle trees, cutting off nutrient flow and eventually killing them.
Wood Wasps (Horntails)
Wood wasps, or horntails, lay their eggs in coniferous trees. The larvae bore deeply into wood and feed for one to several years before emerging as adults. They leave behind large, round exit holes and sometimes bring along a symbiotic fungus that helps break down wood fibers.
Furniture Beetles
Also called common woodworms, furniture beetle larvae attack household wooden items. They prefer moist or slightly decayed softwood and hardwood, creating small round exit holes similar to powderpost beetles. Furniture, beams, and flooring are often affected.
Wharf Borers
These beetles specialize in decayed, waterlogged wood, particularly timbers in marine environments such as docks and wharves. Their larvae feed inside submerged or damp wood, and infestations are most common near coastal areas.
Weevils (Wood-Boring Weevils)
Some weevils, particularly those in the Pentarthrum genus, attack moist, decayed timbers. They prefer wood softened by fungal decay, boring deep galleries and contributing to further weakening. They are often found in poorly ventilated basements and crawlspaces.
Shipworms (Though Technically Mollusks)
While not insects but marine bivalve mollusks, shipworms are often grouped with wood-eating pests because they bore into and consume wooden ships, piers, and pilings. Their behavior parallels that of wood-boring insects, making them an infamous timber-destroyer in marine settings.
Flatheaded Borers (Metallic Wood-Boring Beetles)
The larvae of metallic wood-boring beetles, also called flatheaded borers, feed inside trees and timber. They create oval-shaped tunnels and can take years to mature. They are especially destructive in stressed or weakened trees and are recognized by the D-shaped exit holes they leave behind.
Longhorn Beetles (Cerambycidae Family)
Longhorn beetles are a large family with many species whose larvae bore deeply into both hardwoods and softwoods. They weaken living trees and timber products by feeding on cellulose and lignin. Adults are often large and recognizable by their long, sweeping antennae.
Asian Longhorned Beetle
A notorious invasive species, the Asian longhorned beetle (Anoplophora glabripennis) attacks a wide range of hardwood trees such as maple, elm, and willow. Its larvae tunnel extensively through trunks and branches, disrupting nutrient transport and often killing the tree.
Southern Pine Beetle
This bark beetle is one of the most destructive pests of pine forests in North America. Though it primarily feeds on the phloem beneath bark, its tunneling extends into wood tissue. Massive infestations can devastate entire stands of pines.
Cigarette Beetles (in Wood Packaging)
While primarily known for infesting stored products like tobacco and grains, cigarette beetles (Lasioderma serricorne) have also been found boring into wood packaging, crates, and furniture. Their larvae exploit dry wooden materials as shelter and sometimes as food.
House Longhorn Beetle
This wood-boring beetle (Hylotrupes bajulus) is a serious pest of structural timbers, especially softwoods like spruce and pine. Its larvae create large, oval tunnels and leave behind coarse frass. Infestations can remain hidden for years before signs appear.
Western Pine Beetle
Another bark beetle species, the western pine beetle (Dendroctonus brevicomis) tunnels beneath bark and into sapwood, causing tree death. Infestations are worsened by the fungi they carry, which block nutrient flow in trees.
Lesser Grain Borers (Occasional Wood Feeders)
Though mainly a stored-product pest, the lesser grain borer (Rhyzopertha dominica) also attacks dry wooden articles and packaging. The larvae can bore into hard materials, leaving small circular holes that resemble those of powderpost beetles.
Emerald Ash Borer
This metallic green beetle (Agrilus planipennis) is infamous for devastating ash tree populations across North America and Europe. Its larvae bore serpentine tunnels through wood, disrupting the tree’s vascular system until it dies.
Giant Wood Borers (Prioninae Subfamily)
These large longhorn beetles produce thick-bodied larvae that tunnel through both living and dead wood. They can take several years to develop, leaving behind massive galleries. They are among the largest beetle larvae in the insect world.
Pinhole Borers
Tiny beetles that bore straight, narrow tunnels into both hardwood and softwood. While they don’t consume much wood themselves, they introduce fungi that aid in decomposition and may stain timber. Their damage often shows as pinpoint-sized exit holes.
Beetle Borers of Bamboo (Dinoderus spp.)
These insects specialize in bamboo, boring into culms and feeding on the cellulose. They reduce bamboo to dust and are major pests in regions where bamboo is used for construction, furniture, or crafts.