Treating Powder Post Beetles in Picture Frames

Many things come to mind when thinking about possible damage to artwork: drops, spills, moisture, cracks, and the like. Bugs are just one of the many potential enemies to works on paper that can destroy precious artwork and photos even after a new frame job. Powder post beetles are a common pest known to leave tiny holes in picture frames as well as beams, furniture, toys, and more. The powder post beetle is a kind of wood-boring insect that lives inside of a wooden structure and eats its way through until adulthood. While powder post beetle damage doesn’t happen frequently, we see it from time to time, whether it’s a frame corner that suddenly has wood dust beneath it, or a picture frame sporting fresh holes, like the one you’ll read about below.

Girl With Straw print

Girl With Straw print

This is a Howze Art print we framed in our store in 2014, using acid-free boards and spacers. The frame, which is made from a softwood, was a nice way to offset the funky, bright colors in the picture, Girl with Straw. Fast-forward to the summer of 2015, and we noticed something strange on the right side of the moulding: tiny circular holes. There was only one or two initially, small enough to barely stick a pin into, what could easily be mistaken for a tiny discrepancy in the finish. However, in just a matter of weeks the holes had multiplied, and the culprit was clear.

The powder post beetle in our frame, measuring 1/8" x 3/64"

The powder post beetle in our frame, measuring 1/8″ x 3/64″

Powder post beetles are generally found along the East, South and Western coasts of the United States, and they are one of dozens of species of wood-boring insects. They are considered a pest because they eat through almost any hard or soft wood you can think of. These beetles cause the most destruction as larvae, by tearing through wood completely unnoticed. Once they reach adulthood, they will emerge from the wood, usually between the months of April – July. This process can take months or years, depending on the beetle’s behavior and the size of the wood. The openings they leave behind, known as “shot holes” can leave distracting marks on furniture and frames, damaging the look of a finished piece, or even causing structural damage to a building.

Shot holes left by the beetle

Shot holes left by the beetle

If a female beetle is inside of the wood, it may leave eggs, leading to more generations of infestation within the beam or frame chop. A telltale sign of powder post beetles, besides shot holes, are piles of shredded wood called “frass” that can vary in fineness from the consistency of flour to that of coffee grounds. This often accumulates beneath the holes, which can measure in size from 1/32 to 1/8 of an inch. Anobiid beetles make larger holes, close to 1/8 inch and Lyctid beetles make smaller holes and finer dust, around 1/16 inch.

The best way to prevent wood from having a powder post beetle infestation is by sanding and varnishing the wood and minimizing moisture. Of course, this isn’t possible to do on frames, which have their own lacquers, paint and treatments. This is why conservation framing is important. If a wood boring bug does show up in the wood, it won’t find its way into the frame and leave dust on your print. Powder post beetles only eat wood, so you can find comfort knowing that paper or fabric encased in the picture frame will not be appealing to the tiny critters. But that lovely frame you just purchased is at great risk.

The powder post beetle and exit holes can be seen here

The powder post beetle and exit holes can be seen here

Beetles can be killed easily through fumigation. Once we determined that a beetle was eating his way through our frame, we placed the entire piece inside a plastic acid-free bag along with a Hot Shot! insect strip, found at most hardware stores. Leave the piece alone for a week or two and all beetles should be eradicated. We didn’t have any additional dust, so we opened the back of the piece to find a powder post beetle, which had succumbed to the insect repellent. It’s important to keep close tabs on your framing so you can treat it at the first sign of trouble. Usually one or two small exit holes—if noticeable at all—can be quickly repaired at your local frame shop, or at home if you’re handy. If you wait until the damage is a nuisance, as this frame was, you may have to face the decision of re-framing the entire piece.

We used a Hot Shot strip and clear plastic bag for our frame

We used a Hot Shot strip and clear plastic bag for our frame

You can use large plastic bags such as over-sized acid-free bags or contractor bags for larger frames, but if you have a work that won’t fit into bags of these sizes, you can try a product such as Jecta Gel, which you apply to wood and allow to penetrate, killing all wood-boring bugs with an odorless formula that lasts for years. It’s important to remember that once you treat wood for powder post beetles once, you may have to treat it again depending on the length of time they’ve been present and if any new larvae have hatched inside. Again, the only way to know is to keep a close eye on your frame.

Now that you know a little more about powder post beetles, how to spot them, and how to treat an infested picture frame, be sure to keep a close eye on your artwork. Dust off your pictures from time to time and inspect the surface for any suspicious holes or marks, and don’t delay fumigation if you see these dangerous critters.

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