If you’re buying a house, selling a house, or you think something tiny is eating wood on your property, you will want to know more about wood destroying insects.
Wood destroying insects are insects that eat or damage trees, homes, furniture, and anything else made of wood. Some common wood destroying insects are termites, carpenter ants, and wood boring beetles, such as powderpost beetles and furniture beetles.
In nature, wood destroying insects are important because they hollow out dead trees and clean things up. But that doesn’t mean we want them in our backyards and homes.
Knowing what insects to look for and how to spot the damage they cause can help you buy a house that isn’t infested, prepare for a home inspection, get professional help with treating these insects, or tackle the problem yourself – saving you time, money, and maybe even your home in the long run.
List of insects that destroy wood
Source: Scott Bauer, USDA Agricultural Research Service, Bugwood.org
Here is a list of some common insects that eat, build nests in, damage, or destroy wood:
Ants
Bees and Wasps
- Carpenter bees
- Horntail wasps (though wasps eat many pests in the garden too)
Beetles
- Ambrosia beetles
- Asian long-horned beetles
- Bark beetles
- Deathwatch beetles
- Emerald ash borer
- Furniture beetles
- Longhorn beetles
- Powderpost beetles
Moths and caterpillars
- Carpenter moths
- Clearwing moths
Termites
- Dampwood termites
- Drywood termites
- Subterranean termites
Signs of damage caused by wood destroying insects
Source: Lamar Merck, University of Georgia, Bugwood.org
Over time, wood destroying insects leave signs of damage.
If you find one or more of the following signs in your wood, trees, or home, the property probably has wood destroying insects or had them at some point:
- There is a small round hole drilled in the wood or several holes close to each other
- There are tiny wood shavings lying below these holes
- There are dark spots below the holes
- You find dead insects, such as ants or beetles, near the wood or holes in the wood
- There are tunnels in the wood, either visible from the outside or deep inside
- The wood sounds hollow when you tap on it with the back of a screwdriver
- The wood starts crumbling on the outside, especially on the corners and edges
- The wood gets blisters, which look a lot like water damage
- Support structures start sagging and warping, so doors get stuck, windows don’t open and close properly, ceilings sink, walls start bulging, or floors become sloped
- You find discarded wings near windows and doors, left behind when termites moved in
- You see dark spots of sap on tree trunks
- A branch dies suddenly without warning, or cracks and falls off
What is a wood destroying insect inspection?
A wood destroying insect (WDI) inspection is done by a qualified inspector. During the inspection, the inspector walks around a property to look for signs of wood destroying insects and the damage they cause. The inspector may make recommendations for corrective action, if wood destroying insects are present.
The inspection is a visual one, and things aren’t moved as the inspector walks around the property and all structures on the property. But the inspector will need access to all areas of the building, with a clear view of the walls, windows, and cabinets.
You may need to get a WDI inspection done if:
- Your area is not listed in the Department of Housing and Urban Development’s exception areas and you’re buying a property with the help of the Department of Veterans Affairs, Federal Housing Administration (FHA), or the Department of Housing and Urban Development
- You are applying for a loan to buy a property and the lender (usually the bank) asks for a WDI report, or you want it as part of the home inspection for your own peace of mind
- Your local state or municipality asks for a WDI inspection report
- An appraiser finds an active infestation of wood destroying insects on the property
- You’ve had a wood destroying insect infestation in the past and you want to know if the insects have returned (it’s a good idea to get an annual inspection done in this case)
The inspector fills out a form with the findings from the WDI inspection. Some states have their own forms to be completed, but many will accept the NPMA-33 WDI Inspection Form from the National Pest Management Association (NPMA).
If the inspector is using the NPMA-33 form, they will be looking for signs of carpenter ants, carpenter bees, termites, and wood boring beetles.
Signs of common wood destroying insects
Wood destroying insects can cause a lot of damage to your trees, house, wooden furniture, or any other wooden items. The most destructive wood destroying insects are carpenter ants, carpenter bees, termites, and wood boring beetles. These are the wood destroying insects that inspectors usually look for when doing a wood destroying insect inspection.
Here are the signs to look for if you think you have any of these wood destroying insects in your yard or home:
Signs of carpenter ants
Source: David Cappaert, Bugwood.org
Carpenter ants don’t eat wood but they do dig tunnels in wood to build nests and lay eggs in. These tunnels weaken the structure of the wood, and the wood eventually breaks under some pressure. If you tap the wood with the back of a screwdriver, it will sound hollow where the ants have built nests inside.
Carpenter ants take pride in their tunnels: After digging a tunnel they smooth the walls of the tunnels. The shavings from smoothing these walls get pushed out of the holes.
If you have carpenter ants, you’ll see little piles of wood shavings near the holes in the wood, which may or may not have other dead ants or dead insects in them.
Source: Edward H. Holsten, USDA Forest Service, Bugwood.org
You can also tell you have carpenter ants if you see ants walking in a line, and the ants are larger than the average ant by 1/2 an inch or so.
Signs of carpenter bees
Carpenter bees do not eat wood, but make tunnels in wood for nests.
To identify carpenter bee damage, look for holes that are half an inch wide on the outside of the building or wood, usually with fine sawdust under the holes. The bees often leave yellow or dark markings below the entrances of these holes, which is their excrement.
In these holes, carpenter bees make vertical tunnels where the bees lay eggs. Over time, a nest gets bigger, with more and more tunnels inside the wood.
Signs of termites
Termites are the most destructive and costly wood destroying insect. It can take three to eight years before you see any signs of termite infestation, and by this time the termites will have already caused serious damage to the house or structure.
Termites stay hidden for so long because they like to eat wood from the inside out. Over time, the wood becomes weaker and can crack or splinter under pressure.
Here are some ways to tell if you have termites:
- You see mud tunnels along the outside of the wood
- You notice areas of the wood getting darker or blistering
- When you tap on the wood with the back of a screwdriver, the wood sounds hollow
- You find termite droppings that look like little wood-covered pellets or sawdust
Signs of wood boring beetles
Wood boring beetles, such as powderpost and longhorned beetles, lay their eggs in cracks in wood. When their larvae are born, they are called “woodworms” because they spend the next few months or years eating the wood around them.
Tiny holes and tunnels in your wood around one-sixteenth to one-eighth of an inch wide tell you that beetle woodworms are the problem, especially if you see little sawdust piles around these holes. The woodworms leave this sawdust behind when they chew on the wood.
Source: Stanislaw Kinelski, Bugwood.org
Final thoughts
Wood destroying insects can do all kinds of damage to wood on your property, from your trees or outdoor furniture, to destroying the structural integrity of your home.
Look for the common signs of wood destroying insects, and if you see any of these, call an inspector in to carry out a wood destroying insect inspection and make recommendations on how to tackle the problem.
