powder post beetle damage (C) Daniel Friedman How to Evaluate and Prevent Structural Damage from Powder Post Beetles & Old House Borers

  • POWDER POST BEETLES - CONTENTS: Old House Borer Damage Photographs - How to spot powder post beetle damage and determine its activity. Treatments for Powder Post Beetles & Old House Borers
  • POST a QUESTION or READ FAQs about powder post beetle damage at buildings: how to recognize & assess powder post damage to wood structures
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Guide to powder post beetles & old house borers in buildings.

This article provides powder post beetle & old house borer insect & rot damage photographs, inspection advice, and lists additional articles that discuss the inspection, detection, prevention, and repair of structural damage from insects (termites, carpenter ants, carpenter bees, powder post beetles, and other wood destroying insects), indoor mold, rot and building leaks or water entry.

Our page top photo shows our client holding a screwdriver that penetrated a powder-post-beetle-damaged beam fully to the hilt of the tool - indicating severe structural damage to a beam damaged by powder post beetles.

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Powder Post Beetles - Old House Borer Damage Photographs

Powder post beetle old house borere damage photographs (C) D Friedman D Grudzinski Powder post beetle old house borere damage photographs (C) D Friedman D Grudzinski

In our powder post beetle photos above, while there was significant beam damage, the infestation did not appear active.

Powder post beetle damaged wood will show multiple tiny holes, about 1/8" in diameter, leaving the outermost surface of the wood otherwise intact. Probing you will find powdery sawdust and damaged wood just below this skin. The older the powder post beetle (or old house borer beetle) damage is, the deeper into the wood the damage will extend.

For this reason, strategic probing is important to assess the depth of damage to the wood and thus to the wood structure. When powder post beetles are active you may see light dusting of fine wood powde around some of these holes as well as on surfaces below.

We look for the presence of fine wood powder around the insect exit holes or on the ground below the damaged infected member as indications of recent insect activity. Below left we are probing to determine the depth of insect damage into the beam; at below right is powder post beetle damage in a hand hewn beam. With the absence of fresh fine sawdust powde around the exit holes in these beams one might infer that the insects were not active at the time of inspection.

Powder post beetle old house borere damage photographs (C) D Friedman Powder post beetle damage to hand hewn beam (C) Daniel Friedman

Below are two more photographs of old house borer or powder post beetle damage in a floor support beam. We probe the structural member to find the depth of insect damage as a step in deciding if structural repair, reinforcement, or replacement are needed.

Powder post beetle old house borere damage photographs (C) D Friedman D Grudzinski Powder post beetle old house borere damage photographs (C) D Friedman D Grudzinski

Treatments for Powder Post Beetles & Old House Borers

Powder post beetle damage is typically treated with a topical insecticide spray.

Watch out: it's often the case that this insect pest can appear dormant for a very long time, years, but activity may renew when conditions such as moisture level or temperature change.

Some pest control operators (PCOs) also spray paint the wood surfaces in order to make it easier to spot a renewal of insect activity in the future.

Using Heat or Microwaves to Kill Off Powder Post Beetles or Other Wood Boring Insects

An anonymous reader posted a claim that powder post beetles can be treated by microwave - the comment was deleted as it was basically an advertisement.

However experiments with microwave treatments for powder post beetles have indeed been conducted: wood is heated to 50C (or higher) for 30 minutes.

Watch out: the effectiveness of this treatment varies depending on wood species, moisture content, and other variables, and it may not be cost feasible for some structures or where invasion is extensive. The research is focused on lab and production line treatment of wood, not in-situ treatment in buildings. Excerpting from Fleming et als

Wood temperatures greater than 62°C are lethal to pinewood nematodes and cerambycid larvae infesting red pine in a chamber in which the wood samples remain stationary. Our preliminary findings also suggest, however, that nematodes or larvae in lumber in which the mw field is continuously moving, either by rotation or on a conveyor belt, die at lower wood temperatures than in a batch system without movement. We recommend that additional experiments with non-stationary, commercial equipment be conducted to investigate this phenomenon further. Additional assessment of the effects of conventionally heated vs non-heated mw chambers on lethal mw doses would also be helpful for the commercialization and regulatory process. We can conclude from our experiments that commercial mw treatment (2.45 GHz) of 1-inch thick red pine lumber infested with cerambycids or pinewood nematodes is a feasible alternative to conventional heat treatment or methyl bromide fumigation. - Fleming (2005)

References for Control of Powder Post Beetles / Wood Borers: treatment methods including microwave

How to assess the extent of structural damage from powder post beetles

Details about when, where, how & why to probe wood structural and non-strucural components on buildings are founda

Assessing the extent of structural damage to wood framing members in a conventional building inspection involves the following phases and procedures:

Examples of probing powder post beetle infested wood for structural damage

Clearly the ground-off ice pick wood probe (far left) is finding less-severe damage than the "to the hilt" stab of my dad's screwdriver demonstrated by our client (close left).

Powder post beetle old house borere damage photographs (C) D Friedman D Grudzinski powder post beetle damage (C) Daniel Friedman

Watch out: while we advise against unwarranted cosmetic damage at a building interior, strategic probing of wood sills, rim joists, or floor structures (or other wood members) can disclose severe structural damage that was otherwise not evident. At below left, even our pen was able to easily puncture this termite-damaged joist that had been "cosmetically-repaired" using wood putty

Old House Borer Beetle risk from firewood?

Reader question: old house borers, adult beetles & larvae found in firewood stored in garage

Adult old house borer beetle Hylotrupes bajulus (C) InspectApedia DDWe recently discovered the emergence of hundreds of, what looks like, Old House Borers from firewood that was stacked in our garage.

We've taken the firewood out of the garage now (where we could hear the larvae feeding) but are wondering if there's a possibility that they've infected the house as we have seen dozens crawling around the garage and have found a couple of adult/baby ones in other rooms of the house.

I've attached a picture of the beetle. Any feedback would be very greatly appreciated. - D.D. 6/4/2014


Indeed the beetle in your photo looks like an adult old house borer beetle (Hylotrupes bajulus) -

Close up photo of old house borer beetle exit holes & wood damage (C) Daniel FriedmanRemoving the infected firewood was a smart move. I would not be too nervous about seeing a few beetles or larvae that needed to be cleaned up on a garage floor.

IF the firewood were stored for many months against wood framing, indeed that framing could become infected too - you'd expect to see the small borer openings such as those we show in the article above.

If you see such infection (which is unlikely given the history you cite) send me some photos and I can comment further and of course a local pest control operator can apply a topical pesticide.

At above left I include a close-up photo of old house borer beetle exit holes - these are typically around 1/16"+ in diameter.

If the home has an accessible basement or crawl area that's the place to start inspecting with care.


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