Woodboring Beetle
Wood-boring beetles are beetles whose larvae live inside wood and eat it. They are not one family but several, including bark beetles, metallic wood-borers, longhorn beetles and powderpost beetles. Most help forests by breaking down dead trees, but a few become serious pests.
Wood-boring beetles Quick Facts
| Common name | Wood-boring beetles |
| Scientific name | Coleoptera |
| Kingdom | Animalia |
| Phylum | Arthropoda |
| Class | Insecta |
| Type | Insects (several beetle families) |
| Diet | Wood and bark, eaten mainly by the larvae |
| Habitat | Forests, woodlands, timber and wooden objects |
| Native range | Worldwide |
| Size | Mostly a few millimeters to a few centimeters |
| Lifespan | Life cycle from a few months to several years |
| Special feature | Larvae tunnel through wood and leave exit holes |
How Wood-Boring Beetles Live
The adult female usually lays her eggs in cracks in bark or in the pores of bare wood. The larvae, often called woodworms, hatch and chew tunnels as they feed. When they are fully grown, they pupate inside the wood. The new adults then chew their way out, leaving small exit holes.
Wood is hard to digest and not very nutritious, so many wood-borers grow slowly. Some take a year or more to become adults, and in very dry wood a few have taken many years.
Bark Beetles
Bark beetles are tiny weevils, often only a few millimeters long and reddish-brown to black. There are around 6,000 species. Scientists once put them in their own family, but they are now known to be part of the true weevil family, Curculionidae.
Most bark beetles tunnel just under the bark, carving patterns that look like little maps. Well-known kinds include the large elm bark beetle (Scolytus scolytus) and the smaller European elm bark beetle (Scolytus multistriatus), which spread Dutch elm disease. The European spruce bark beetle (Ips typographus) can kill large areas of spruce forest, and the coffee berry borer (Hypothenemus hampei) is a major pest of coffee farms around the world.
Metallic wood-boring beetle – Photo by: Katja Schulz
Metallic Wood-Boring Beetles
Metallic wood-borers (family Buprestidae) are also called jewel beetles because many have shiny, rainbow-like colors. Their bodies are long and bullet-shaped. A few grow up to about 8 cm long, but most are under 2 cm.
Their larvae are called flat-headed borers because the area just behind the head is wide and flat. They tunnel through trunks, branches and roots, usually in trees that are dying or stressed.
An adult emerald ash borer on a penny
Emerald Ash Borer
The emerald ash borer is a small, bright green jewel beetle from Asia. Unlike most of its relatives, it attacks healthy ash trees. Since it arrived in North America, it has killed millions of ash trees.
Common tuft-bearing longhorn beetle – Photo by: Aleksey Gnilenkov
Longhorn Beetles
Longhorn beetles (family Cerambycidae) get their name from their very long antennae, which can be longer than their bodies. They use these antennae to smell mates and food. Together with a few small related families, they include more than 35,000 known species.
Their larvae are called round-headed borers. Most feed on dead or dying wood, but some, like the Asian longhorned beetle, attack living trees and cause great damage.
Small Relatives of Longhorns
Distenia gracilis
Disteniidae are slender beetles that are mostly active at night. They are found mainly in warm regions, and their larvae bore into the wood or roots of broad-leaved trees.
Oxypeltidae – Photo by: Hectonichus
Oxypeltidae is a tiny family found only in the Andes of Chile and Argentina. The larvae bore into southern beech trees (Nothofagus), and the adults are active during the day.
Vesperus beetle – Photo by: entomart
Vesperidae is another small family related to longhorns. Their larvae live underground and feed on the roots of plants.
Weevil
Weevils
Weevils, or snout beetles, have a long beak with tiny jaws at the tip. Most are small, often less than 1 cm long, and dark in color. Many feed on seeds, nuts and plants, and some bore into wood. Their larvae are pale, legless grubs, and you may find them inside nuts or seeds.
Wood-Boring Beetles in Our Homes
Most wood-borers live in forests and rarely come indoors. When they do, it is usually inside firewood. Three groups, however, can infest dry wood in houses: powderpost beetles, false powderpost beetles and deathwatch beetles.
Powderpost beetle – Photo by: Wisut Sittichaya, Roger A. Beaver, Lan-Yu Liu, Aran Ngampongsai
Powderpost Beetles
Powderpost beetles are small, reddish-brown beetles. Their larvae turn wood into frass, a mix of wood dust and droppings that is as fine as flour or talcum powder. Little piles of this powder below tiny round holes are a sure sign of them.
They attack hardwoods with large pores and plenty of starch, such as ash, oak, hickory, walnut and mahogany, as well as bamboo. They can live in quite dry wood, so they may infest floors, paneling, furniture and moldings. Their life cycle usually takes from a few months to about a year.
Deathwatch beetle – Photo by: Sarefo
Deathwatch Beetles
Deathwatch beetles are close relatives of the cigarette beetle and drugstore beetle. The best-known is the European deathwatch beetle. Adults tap their heads against the wood to call to mates. Long ago, people sitting quietly at night beside a sick person heard this ticking and gave the beetle its spooky name.
These beetles prefer damp wood, often old wood that is starting to decay. Homes that are kept dry are less likely to have them. Their frass is gritty and made of tiny pellets, and their life cycle often takes several years. In North America, the Pacific deathwatch beetle (Hemicoelus gibbicollis) is a common example.
False powderpost beetle – Photo by: Clemson University – USDA Cooperative Extension Slide Series
False Powderpost Beetles
False powderpost beetles (family Bostrichidae) are dark brown or black, often with reddish legs and antennae. Their thorax forms a hood, so the head cannot be seen from above. Many are about 6 mm long.
Unlike other house-infesting borers, the adults bore into wood to lay their eggs. The larvae leave coarse frass. They often arrive in imported bamboo or timber. One species, the lead cable borer, is famous for chewing through the lead coverings of old cables, and some kinds bore into wine barrels.
Why Wood-Borers Matter
In forests, wood-boring beetles are important recyclers. By breaking down dead and dying trees, they release nutrients back into the soil and make space for new growth. Their tunnels also become homes for fungi and other small creatures.
Most of the damage they cause in homes is cosmetic, meaning it spoils the look of the wood without making it weak. Serious damage to beams usually only happens after many years of heavy infestation.
Keeping Them Out of Your Home
- Store firewood outdoors, off the ground and away from the house, and bring in only what you will burn soon.
- Buy firewood locally, and do not move it long distances, which can spread pests like the emerald ash borer.
- Use kiln-dried timber for building and furniture.
- Seal, paint or varnish bare wood, since many beetles lay eggs only in unfinished wood.
- Keep crawl spaces and basements dry with good ventilation.
- Replace small infested pieces of wood, and ask a professional to check if structural timbers are affected.
Wood-boring beetles FAQs
What are the signs of wood-boring beetles?
Look for small round or oval exit holes in wood, often with little piles of powdery dust called frass below them. Weakened or crumbly wood surfaces can also be a sign.
Are wood-boring beetles harmful to people?
No. Wood-boring beetles do not sting or spread disease. They can damage wooden objects and, in rare heavy infestations, timbers in buildings.
Why is it called a deathwatch beetle?
Adults tap their heads on wood to attract mates. Long ago, people keeping watch at night beside someone who was dying heard the ticking sound and linked it with death.
How do wood-boring beetles get into houses?
They usually arrive inside firewood, furniture, bamboo or timber that already has larvae in it. Some adults also fly in and lay eggs on bare, unfinished wood.
Are wood-boring beetles good for forests?
Yes. Most attack dead or dying trees and help break them down, which returns nutrients to the soil. Only a few species, like the emerald ash borer, kill healthy trees.
Randi Jones is the owner and founder of the Nature Gift Store, an online retailer specializing in nature-themed gifts, educational science projects, live animal nature kits and real butterfly artwork. A biology graduate who fell in love with insects, she founded the company in 2001 to make active learning about nature fun, accessible and engaging for children and adults. Her store offers real butterfly frames, home and garden decor and educational live animal kits, including ant farms, worm farms, tadpoles, ladybugs and hermit crabs, and she runs a bug museum in Washington featuring live animals like Eddie the Iguana alongside other reptiles and insects.
