There are 4 categories of common wood-boring insects: carpenter ants, termites, bark beetles and wood borers, and powderpost beetles. Each of these insects does damage to wood over time, and it’s likely they were present before you noticed them. It’s important to accurately identify them before beginning pest control, so take your time to make sure you get it right.
What are Wood-boring Insects?
Wood-boring insects are a selection of arthropods that damage wooden structures. This group of insects consists of both larvae and adults.
Wood-boring and wood-destroying insects are considered pests because of the damage they cause to both residential properties and plants. While some of these insects still play a role in the ecosystem, they can be a great nuisance in large numbers. In some cases, wood-boring insects can cause structural damage to both homes and woody plants.
Carpenter ants are commonly found in forested areas all over the globe. And while most wood-boring insects are known to eat wood, carpenter ants actually don’t. Instead, these ants build nests in the wood by making tunnels in them, particularly in damp or rotting wood. They rarely damage sound wood, but once a nest is built, it allows moisture to build, leading to more wood rot.
Carpenter ants vary in size from 1/2 inch to 5/8 inch long and can be black, a combination of black and red, red, or brown. Signs of a carpenter ant infestation include small holes in wood with sawdust and other debris below them. Carpenter ants don’t eat the wood they chew up and will instead remove it, and other debris, from their nests.
Carpenter ants are usually a sign of a moisture problem, so a good place to start looking for nests is near windows and doors where you would expect excess moisture. You can leave small bits of pet food or bread near these areas and follow ants as they take it back to the nest.
Signs and Prevention
The best place to start is with moisture. Keep an eye out for moisture problems around your home — keep siding properly maintained and sealed to prevent moisture from entering. You should also eliminate any standing water around your property.
Keep cracks under doors and around windows sealed. Because pests will sometimes use plants as a bridge into your home, keep branches cut back away from your house.
This is an insect you most likely want to contact a professional for extermination. Because carpenter ants can cause significant structural damage, it’s important to have a plan in place for finding and completely exterminating the main nest as well as any satellites. The main nest will usually be outdoors, while satellite nests may form indoors, and will house only worker ants.
You will also need to assess any structural damage to your home and begin repairs.
Carpenter ants are often mistaken for termites because of their similarities. Unlike carpenter ants, termites use wood for food. The best way to tell termites from ants is by their wings. Ants have front wings that are longer than their hind wings, while those of termites are the same size. Their antennae also bend at a right angle, whereas termites’ are at a straight angle.
There are several types of termites that destroy woods: drywood termites, formosan termites, dampwood termites, conehead termites, and subterranean termites.
Drywood termites. Drywood termites do not require contact with soil like other types and infest dry wood. You might find them in roofing, wooden wall supports, and in damaged wood around the house. They’re more prevalent in Southern states from North Carolina to the Gulf of mexico and East to California and other coastal states.
Formosan termites. Formosan termites are originally from China, but can now be found in Hawaii, North Carolina, South Carolina, Georgia, Virginia, Texas, Louisiana, Alabama, Florida, Tennessee, and California. These termites build large mud nests inside walls and are difficult to control once they’re inside.
Dampwood termites. Dampwood termites, as their name suggests, need moisture. They’re larger than other termites and don’t usually infest structures because they lack the levels of moisture needed. However, if you have a moisture problem, they can be a concern.
Dampwood termites are found in states along the Pacific coast and can also be found in Florida.
Conehead termites. This extremely aggressive species is known to cause a lot of property damage in a very short period of time compared to other termites. They have reemerged in Florida recently after previously having been thought eradicated.
Unlike other termites, conehead termites do not rely on tunnels to travel, but will travel along the ground like ants.
Subterranean termites. Subterranean termites hold the title for the most destructive species of termite in the U.S., and they are found in every state except Alaska. They live in moist environments, usually in the soil, and can build colonies of up to 2 million members.
Signs and Prevention
Eliminating moisture around your home and sealing up potential entrances can help prevent termites from gaining access. Repair any damage to soffits and roof shingles.
Keep an eye on exterior wood around windows and doors for any changes, and maintain an 18-inch gap between wooden areas of your home and soil. You should also inspect your foundation yearly for mud tubes.
Signs of a termite infestation include seeing insects inside your home and finding mud tubes in or near your home. Mud tubes are used by termites for travel and they’re usually about the diameter of a pencil.
Seeing termite swarms near your foundation can also indicate termite presence in your home. Swarms happen during the spring when termites are looking for new areas to colonize.
You’ll know if an infestation is active if the tube is broken and you see small, white worker termites. If the tube is empty, it can either be that the infestation is inactive or that the worker termites have temporarily left it. This happens when termites forage somewhere else in the structure.
Another sign is wood that is hollowed out along the grain. You can also spot small pieces of dried mud or soil along the galleries. Sometimes, there are also tiny holes in the drywall with bits of soil around. Sunken traces behind the walls can also be a sign of active termites.
Termites cause billions of dollars in property damage every year — including structural damage. And some species are aggressive and difficult to eliminate. This is another insect you want to enlist an exterminator for.
Because of the aggressive nature of these pests, DIY extermination methods are unlikely to solve your problem. A licensed professional can help find and exterminate termites throughout the structure and offer advice on preventing future infestations.
Wood Borers and Bark Beetles
Wood borers. Wood borers target weakened or recently damaged wood to deposit their eggs. Wood borer larvae will tunnel or bore into solid wood, emerging from the hole as adults.
There are several different types of wood borers native to the U.S., including roundheaded wood borers, flatheaded borers, and ambrosia beetles.
Roundheaded wood borers, called longhorned beetles as adults, vary in length between 1/4 inch and 3 inches. They have long antennae. Larvae are slender, white to yellow in color, and have no noticeable legs.
Flatheaded borers are called metallic woodboring beetles as adults because of their often shiny and beautifully colored bodies. They have boat-shaped bodies and are 1/2 inch to 1 inch long.
Larvae have a flattened thorax, are 1/4 inch to 2 inches long, white to yellowish in color, and legless.
Ambrosia beetles are tiny and females introduce a white fungus, called ambrosia, into the tree that larvae feed on after hatching. Beetles are dark in color.
Bark Beetles. Bark Beetles feed in between the wood and the bark and also generally attack weakened trees. They will go dormant during the winter and then become active again in the spring.
Bark beetles are small, about the size of a grain of rice, and can be black, brown, or red in color. They have strong mandibles for chewing. Grubs are usually off-white, and have a dark brown head.
Both wood borers and bark beetles can cause damage to trees, plants, log homes and certain wood furniture. Wood borers and bark beetles feed on the innermost layer of the bark, called the cambium, where nutrients are carried throughout the tree. Once they’ve eaten around the entirety of the cambium, called girdling, the tree will die past that site.
Boring can also weaken branches and make trees susceptible to disease.
Signs and Prevention
Wood borers and bark beetles will leave behind a sawdust-like excrement that you may find mixed with sap near holes. The holes can be round, oval, or semicircular and will appear randomly placed on the tree.
Since most wood borers and bark beetles attack weakened trees, the best way to prevent them is to keep trees healthy. Provide ample water during dryer seasons and provide soil correction when necessary.
Avoid injuring above ground roots and remove dead wood and prune annually. You can wrap newly transplanted trees to prevent egg depositing in thin bark. Certain pesticides can be used to prevent these insects as well.
Heavily infested or damaged trees may not recover or even benefit from pesticide use. To prevent further spread, removal of infested or diseased branches and limbs can be attempted. You might also consider removing the affected plant altogether to prevent spread to healthy plants.
Coming in second to termites in terms of their ability to damage dry wood are powderpost beetles, though they damage wood slowly. Powderpost beetles have been known to damage wood flooring, wood instruments, hammer handles, timber, and so on.
They’re often a problem during renovations of old structures, like barns. They get their name from the fine, powdered sawdust they leave behind as they chew through wood.
Adult powderpost beetles are less than 1/4 inch in size and can be reddish-brown to black in color. Larvae are white or cream in appearance and create small, meandering tunnels through the wood as they feed.
Signs and Prevention
If you notice fine sawdust, it may resemble flour, accompanied by shotgun-like holes, you can dust off the sawdust and check back a couple of days later to see if more sawdust has accumulated. If it has, you may have an active infestation. Since most activity happens during the warmer seasons, you may want to wait until them to try this method of checking.
You’re unlikely to see the beetles or larvae themselves since all of the activity happens beneath the surface of the wood. But you can sometimes tell the difference between an active infestation and an inactive one by the weathering of the wood.
Active infestations will have holes that do not show the same weathering as the exterior wood. Active infestations will also not have any wood finish or paint in them.
Most infestations occur in lumber or manufactured items. Adults will lay eggs in untreated wood, so all lumber should be inspected for damage before using it. Most sealed or finished wood is generally safe from infestation, though if infestation happened before it was sealed, reinfestation can occur.
If you notice an infestation in finished wood, sealing it or refinishing it can take care of the problem.
Often, infestations are limited to a small area and replacing the wood in that area can solve the problem. Heat can also be used to kill powderpost beetles, and most lumber is kiln dried between 125 and 140 degrees F, which is sufficient to kill powederpost beetles at all life stage.
If beetles have infested the lumber since then and reinfestation occurs, heat chambers can be used for certain pieces of furniture. For smaller items like wood carvings or picture frames, freezing temperatures can also be used. Bag the item, and place it in the freezer, below 0 degrees F, for 3 to 7 days.
Moisture control is also an effective method. Many species of powderpost beetle have high moisture requirements — above 14%. Installing moisture barriers in crawl spaces and covering soil with polyethylene sheeting can protect wood structures from excess moisture. Improving drainage and increasing ventilation under homes is also a good way to reduce moisture.
You can also use pesticides, like borate sprays on unfinished wood. They won’t work on finished wood, since they won’t be able to penetrate the surface and reach the beetles. They are usually most effective when used in structural wood elements, like joists and beams.
Fumigation is also an option, but it’s costly and not always effective. If the infestation has spread to the walls between floors, and other areas where surface treatment isn’t possible, structural fumigation may be used. This should be considered only in extreme cases.