On this page
How to identify it
- Adults are small, slender beetles, usually under 1/4 inch long and brown to reddish brown; Kentucky gives 1/16 to 1/4 inch for the lyctid powderpost beetles.[1][2][3]
- Exit holes are small and round and tend to be all the same size. Sources give slightly different sizes (see below).[1][2][4][3]
- The dust (frass) is very fine and feels like talcum powder or baking flour when rubbed between your fingers. It is packed into the tunnels and sifts out of exit holes into small piles.[1][3]
- Only the very tip of a click-type ballpoint pen fits into a powderpost beetle exit hole.[1]
- Dead adults often collect on windowsills, because emerging beetles fly toward light. The adults are active mainly at night, so you are more likely to see damage than beetles.[1][3]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Deathwatch beetles (Anobiidae) | Prefer damp wood and mainly attack softwoods such as Douglas-fir, often in crawl spaces and basements; their frass feels gritty, their holes vary in size, and a pen's tip plus part of its angled face fits in the hole.[1][3] |
| False powderpost beetles (Bostrichidae) | Dark brown or black and humpbacked, so the head is hidden from above. Their coarser, meal-like frass stays tightly packed in the tunnels, and the whole pen point usually fits the hole.[1][3] |
| Drywood termites | Leave larger, granular, pepper-like pellets with ridged sides, not fine powder.[1] |
| Drugstore beetle | A stored-food pest closely related to the deathwatch beetles, not to true powderpost beetles; it turns up near pantry foods, not wood.[1][3] |
| Foreign grain beetle | A tiny (about 1/16 inch) brown beetle, often abundant in new homes, that feeds on molds growing on damp lumber or drywall. It doesn't damage wood and disappears once the moisture problem is fixed.[3] |
Where it lives
Found in dried hardwood products; species common in California structures include the old world, southern and western lyctus beetles, and key structural species have spread worldwide in wood packing and products.[1]
Biology and life cycle
Females lay eggs in the pores, cracks and old exit holes of unfinished hardwood; Kentucky gives 10 to 50 eggs per female. Open-pored woods such as oak, ash, hickory, mahogany, walnut and bamboo are favored.[1][2][3]
The larvae need starch in the sapwood. Kentucky says females won't lay eggs in wood with less than about 3 percent starch. Lyctids can attack wood as dry as about 8 percent moisture, while softwoods lack suitable pores and starch.[1][3][2]
Larvae are small white grubs about 1/5 inch long that feed inside the wood and do the damage; they overwinter there and become adults in spring.[2][1]
How long a generation takes depends on temperature, humidity and wood quality. Estimates vary (see below).[1][4][3]
Beetles usually get into lumber while it is stored and cured, or during transit, and emerge later from the finished flooring, paneling, cabinets or furniture. Kentucky says lyctids typically start emerging within a year of processing, so infestations show up mostly in new homes or new articles.[2][3]
As wood ages its starch declines, so lyctid infestations eventually die out even without treatment, although a few beetles may keep emerging for up to about five years.[3]
Damage and signs
- Larvae damage wood paneling, molding, flooring, window and door frames, plywood, bamboo articles and furniture; old furniture and antiques are especially vulnerable.[1][2][3]
- Kentucky ranks powderpost beetles second only to termites in damaging dry, seasoned wood, but says they work slowly, so there's no need to act immediately for fear of losing a home's structural integrity.[3]
- Lyctids rarely attack structural framing such as studs and joists, which is usually softwood; in hardwood plywood the damage usually stays in the hardwood layer.[3][4]
Health risk
The beetles are a threat to wood, not people. One related caution comes from Europe: a tiny mite, Pyemotes ventricosus, a parasite of the furniture beetle, causes itchy dermatitis in people. A 2008 study in Emerging Infectious Diseases traced it in 42 patients in 23 houses in southeastern France, a 2022 review found contact with infested furniture to be a main risk factor in outbreaks, with symptoms usually ending within a week, and a Spanish case followed restoring woodworm-infested furniture.[1][5][6][7]
Control
Prevention
Prevention is the best approach, because infestations are hard to control once started.[1]
Before treating, confirm the infestation is active. Fresh powder the color of new-cut wood, crisp holes that haven't weathered, and holes with no stain inside on stained wood point to activity. Mark or seal existing holes, clean up the powder, and recheck later, ideally in spring or summer.[3][1]
Seal bare wood with paint or varnish so beetles have no pores or cracks for eggs, and inspect furniture, lumber and wooden items before bringing them indoors. Old lumber from a barn or woodpile is behind many serious infestations.[1][2][3]
Sanitation
Bring in only the firewood you will burn that day, and don't store valuable items in barns or sheds, which are often infested.[1][2]
Traps and physical control
Remove and replace infested wood when possible, along with adjacent boards as a precaution, and burn the old wood or take it to a landfill. Kentucky suggests waiting at least six months before refinishing a whole floor in case more holes appear.[1][3]
Small wooden items without fabric or paint can be heated in an oven at 120° to 140°F for 6 hours or frozen at 0°F for 72 hours, longer for wood thicker than 2 inches.[1]
Pesticides
Borate (sodium borate) sprays on bare, unfinished wood can kill larvae inside and block newly hatched ones. They can't penetrate paint, varnish or wax, and in dry wood they may reach only the top 1/4 inch; UC says a licensed pest control operator must apply them.[1][2][3]
When to call a professional
Licensed operators can fumigate furniture in a chamber or a whole building. Fumigation doesn't prevent reinfestation, Kentucky notes current sulfuryl fluoride fumigants are less effective against wood-boring beetles than the methyl bromide no longer available, and portable items can be fumigated more effectively and cheaply than a whole house.[1][2][3]
Where sources disagree
What counts as a powderpost beetle: UC uses the name for the lyctine beetles only and treats deathwatch and false powderpost beetles as separate groups, while Kentucky and NC State use it for lyctids, anobiids and bostrichids together. This page covers the lyctid kind.[1][3][4]
Hole size: Penn State gives 1/16 to 1/8 inch, NC State 1/32 to 1/16 inch, and Kentucky calls lyctid emergence holes about the size of a pinhead.[2][4][3]
Life cycle: UC gives 3 months to more than a year; NC State says as little as three months but more typically 9 to 12 months; Kentucky says under a year in newly seasoned wood and two or more years as starch declines.[1][4][3]
Reinfestation: Penn State says many continue to breed in an infested piece of wood for generations, while Kentucky says lyctids and bostrichids have a hard time reinfesting wood after emerging indoors, so borate treatment of floors is seldom necessary.[2][3]
Heat and cold: UC gives 120° to 140°F for 6 hours, or 0°F for 72 hours; Kentucky gives 120° to 135°F for up to 24 hours depending on thickness, or 0°F for 3 to 7 days.[1][3]
Common questions
- How do I know if the holes are still active?
- Look for fresh, light-colored powder under the holes, new holes that haven't weathered, and new beetles on windowsills. Yellowed or caked powder covered with dust is probably old.[3][1]
- Can powderpost beetles attack my varnished furniture?
- Sanded and varnished wood normally isn't attacked, because adults can't find crevices for eggs, though beetles already inside can still emerge through the finish.[2][3][1]
- I bought an antique with lots of holes. What should I ask?
- Ask the dealer for a receipt from the company that fumigated it.[2]
- Do I need to treat right away?
- Usually not. Kentucky says powderpost beetles damage wood slowly and lyctid infestations often die out on their own, so confirming activity first and waiting to see often makes the most sense.[3]
Sources
- University of California Statewide IPM Program, “Pest Notes: Wood-Boring Beetles in Homes, Publication 7418.” ipm.ucanr.edu/home-and-landscape/wood-boring-beetles-in-homes/ (accessed 2026-11-11)
- Penn State Extension, “Powderpost Beetles (updated June 24, 2026).” extension.psu.edu/powderpost-beetles (accessed 2026-11-11)
- University of Kentucky Department of Entomology, “Powderpost Beetles, ENTFACT-616 (Potter; revised March 2026).” entomology.ca.uky.edu/ef616 (accessed 2026-11-11)
- NC State Extension, “Powderpost Beetles and Wood-Inhabiting Fungi (Residential, Structural and Community Pests).” content.ces.ncsu.edu/powderpost-beetles-and-wood-inhabiting-fungi (accessed 2026-11-11)
- Emerging Infectious Diseases (CDC), via PubMed, “Del Giudice et al. (2008), Pyemotes ventricosus dermatitis, southeastern France.” pubmed.ncbi.nlm.nih.gov/18976564/ (accessed 2026-11-11)
- Infectious Disease Reports, via PubMed, “Vellere et al. (2022), Pyemotes ventricosus dermatitis: a case report and an extensive review of outbreaks and clinical cases.” pubmed.ncbi.nlm.nih.gov/36136822/ (accessed 2026-11-11)
- Skinmed, via PubMed, “Sanchez-Bernal et al. (2020), Pyemotes ventricosus dermatitis: comet-shaped skin lesions after contact with woodworm-infested furniture.” pubmed.ncbi.nlm.nih.gov/33160441/ (accessed 2026-11-11)
- iNaturalist, “Lyctus brunneus taxon page (order and family).” www.inaturalist.org/taxa/329510 (accessed 2026-10-06)