Search no further for an article that will answer all your questions about the elusive powder post beetle and its relationship to furniture.
Have you ever seen tiny pin holes in your furniture? Ones that just appear for some reason. Collecting directly under the holes you will see a very neat pile of fine sawdust powder. At first, you may wipe the sawdust away- not knowing what actually caused it, but in a couple of days you find that it has appeared again in another neat little pile. After careful inspection, you find the source which is a tiny little hole. You have a powder post beetle.
Identification and Behavior
Powder post beetle is a term used to describe several species of small (1/8-3/4 inches long), wood-boring insects which reduce wood to a fine, flour-like powder. Although there are types that infest just about any type of wood (soft or hard), we will discuss the most common type, the Lyctid. It is usually found in hardwoods that furniture is made from.
Holes made by lyctid beetles are about the diameter of a pinhead whereas exit holes made by other species are slightly larger. Lyctid frass (powder) is extremely fine and feels like talc or flour when rubbed between the fingers. Other beetle frass is also powderlike, but feels gritty. Fresh powder indicates an active infestation. If there is no powder in close proximity to the holes, or no fresh powder is deposited after the area has been cleaned, then it may be inactive due to the mature beetle exiting the piece.
The boring is done by the larvae as they create narrow, meandering tunnels in wood as they feed. They will usually stay within the very board that they are in, and will eat the wood inside right up to the surface. Sometimes you can tap the wood surface to detect the tunnels by the hollow sound of the tapping. The holes you see are not entry holes though. These are exit holes where the larvae discard the wood fibers after depleting them of the starches they need for food. The holes will also be the exit for the adult once it has matured. Newly-emerged adults will search for a mate in order to lay eggs on or below the surface of bare wood (including trees or unfinished lumber).
Eggs can lay dormant for 1 to 5 years. One expert exterminator has stated that Mother Nature has actually enabled the eggs to lay dormant for decades before hatching. He came to this conclusion due to the treatment of infestations in antiques. Remember that the tiny holes are created as an exit. According to most experts, the eggs were laid in the wood before it was manufactured into a piece of furniture no matter how old it is. You’re just not going to find these insects buzzing around inside your home, mating, and damaging your belongings.
The eggs hatch into tiny larvae which bore into the wood, emerging as adults months later. After feeding for an extended period, the larvae will enter the pupal stage to mature. Adult beetles are rarely seen because their life span is usually a short one, and they are most active at night. I have personally only seen one live beetle even though I have seen dozens and dozens of pieces of furniture with “shot-holes”. I felt lucky to have actually held one in my hand after trying to find them for years.
Imported tropical hardwoods are especially prone to lyctid beetle attack because of poor storage and drying practices prior to shipment to this country. Lumber used to construct houses in the United States are not usually prone to have infestations because of the softer wood (pine) that is used. Many people are concerned their homes are at risk of an infestation when they find evidence of a powder post beetle, but I’ve never heard of a single account of a beetle infesting other areas of a home. This is most likely because: 1- they need a mate in order to reproduce, and 2- They will not deposit eggs into wood that is finished (like furniture, cabinets, and hardwood floors). They need raw hardwood with a crevice to lay the eggs in. Your belongings are pretty safe.
In almost all cases, infestation results from wood that contained eggs or larvae at the time it was placed in the home. This is why most furniture retailers and manufacturers react quickly when an infestation is noticed. The responsibility lies with them, and not a homeowner. Typically, the infested piece was constructed from wood which was improperly dried to an acceptable moisture level (below 10%) or it may have been stored with contaminated boards of raw lumber long enough for adult beetles to lay eggs in.
Prevention and Control
Builders can prevent infestations by using Borates to treat raw wood. They will protect the wood for up to 40 years. Manufacturers can stop active infestations in their lumber by properly drying the lumber to a moisture level below 13% in addition to applying chemicals, but many manufacturers in Asia have a difficult time achieving acceptable moisture levels due to the humid environment. Once furniture is constructed, it may not show evidence of beetles for many years, but I have opened pieces from inbound containers that have visible sawdust on pieces that are just weeks old.
Once a piece has been determined to contain a beetle, it must immediately be quarantined in a warehouse environment while other items on the same container are inspected. Just because one piece of furniture has an infestation, it doesn’t mean that other items will have the same problem, but it is impossible to determine that unless you can find an exit hole with fresh powder residue on the other pieces. To be safe, it is advisable to try to control (exterminate) any beetles that may be in other pieces of furniture that come from the same origin. There are only 2 ways to guarantee that any eggs, larvae, pupae or adult beetles are killed: fumigation or freezing.
Fumigation is effective when done correctly. Since it is very expensive, it must be performed correctly by a licensed technician to get your money’s worth. This means that the piece must be opened (uncased) and fumigated in a chamber for at least 5 days in the gas filled environment. The chemicals will enter the wood pores and chambers to kill any active beetles. The furniture has to be exposed to the chemicals for days in order to get the penetration needed to kill the insect. Any treatment or chemical that is merely applied to the surface will not harm the insect at all and will be completely ineffective. There is no way for a do-it-yourselfer to rid a piece of furniture of the beetle by trying to fog, or bug bomb the item under a plastic bag. People have tried this for years with no long term success. Use a professional and ask them what their procedure is, and if it comes with a guarantee.
Freezing is a good approach, but it too has to be done correctly. If an item can be placed in a large walk-in freezer for 5 days at a consistent temperature of 32 degrees Fahrenheit (0 Celsius) or less, it will kill any egg or larvae completely. This should not damage the furniture as long as it is kept dry during this time period. Remember that powder post beetles thrive in warm, moist environments and cold arid air is their enemy. For large quantities of items, a tractor trailer that has refrigeration may be a good alternative since any furniture that is boxed or crated can be left in the original packaging and frozen while the trailer is parked at a bay. This method is less costly, more effective, and can bring peace of mind when there is a question of infestation.