Do Termites Eat Pressure Treated Wood? Unveiling Their Appetite

Termites are notorious for causing extensive damage to wooden structures by consuming wood as a primary food source. The key to preventing termite infestations lies in understanding which wood types are more resistant to their attacks. Pressure-treated lumber has long been a popular choice in construction because of its increased resistance to rot and insects.

Pressure-treated wood is lumber that has been chemically treated to protect it from decay-causing organisms and wood-destroying insects, such as termites. However, it is worth noting that while treated wood is more resistant to termite attacks, it is not completely immune. Depending on the specific type of treatment and the species of termite involved, pressure-treated wood may still be at risk of infestation. For instance, subterranean termites have been known to build their shelter tubes over chemically treated wood and infest untreated wood above it.

Understanding Pressure Treated Wood

Preservatives Used

Pressure treated wood is lumber that has been treated with chemical preservatives to protect it from rot, decay, and insect infestation. Some common preservatives used include:

  • Alkaline Copper Quat (ACQ): A water-based treatment that is less toxic than older options like chromated copper arsenate. ACQ-treated wood provides resistance to fungi, bacteria, and insects.
  • Alkaline Copper Quaternary (ACQ): Another name for alkaline copper quat.
  • Copper Azole (CA): A copper-based preservative that offers protection against fungal decay and insects. CA treated wood is suited for outdoor applications and ground contact.
  • Chromated Copper Arsenate (CCA): An older, now less commonly used treatment due to its toxicity concerns. It provides protection against decay, insects, and marine borers.
PreservativeToxicityProtection Against
ACQLowFungi, bacteria, insects
CALowFungal decay, insects
CCAHighDecay, insects, marine borers

Process of Pressure Treatment

The process of pressure treating wood involves placing lumber in a horizontal cylinder and subjecting it to cycles of pressure and vacuum. The cylinder is flooded with the chosen chemical preservative during the treatment. Pressure treatment methods can be generally classified into two groups:

  • Full-cell processes: Aim to saturate the wood with as much preservative as possible.
  • Empty-cell processes: Leave more air than preservative inside the wood cells, resulting in less chemical usage and weight.

Types of Wood Commonly Treated

Pressure treated wood is most often used in outdoor residential settings and for structures that are exposed to moisture or insect infestation. Examples of treated wood applications include:

  • Decking
  • Pergolas
  • Playground equipment
  • Outdoor furniture
  • Fencing
  • Garden beds

Some common types of lumber pressure treated include:

  • Southern yellow pine
  • Spruce
  • Pine
  • Fir

These woods are chosen for their affordability and availability, as well as their ability to absorb and retain the preservative chemicals.

Termite Infestations and Wood

Common Types of Termites

There are three main types of termites:

  • Subterranean termites: These termites live in soil and build their colonies underground. They are the most destructive variety and typically infest wood that is in contact with the ground.
  • Drywood termites: They infest sound, non-decayed wood in structures such as wood flooring, attics, wood frames, and furniture1. These termites can survive in temperatures from 60°F to 110°F2.
  • Dampwood termites: These termites prefer moist, decayed wood and are usually found in damp or humid environments.

Signs of Termite Infestation

Some key indicators of termite infestations include:

  • Mud tubes: Subterranean termites create tunnels made of mud to travel between their nest and food source.
  • Swarmers: Winged termites, called swarmers, leave their colony to find a mate and establish a new colony.
  • Droppings or fecal pellets: Drywood termites leave behind droppings, which are about 1/16″ long3.
  • Damaged wood: Wood that sounds hollow when tapped or has visible cracks and holes may be infested.

How Termites Feed on Wood

Termites digest cellulose found in wood using special enzymes in their stomach. While some trees contain natural chemicals that repel or kill termites, they still feed on various types of wood4. For instance, termites prefer southern yellow pine and spruce, while they struggle to survive on a diet of teak.

Comparison of Wood Types and Termite Resistance:

Wood TypeTermite Resistance
Southern Yellow PineLow
SpruceLow
TeakHigh
Peruvian WalnutMedium

Pressure treated wood incorporates chemicals to prevent termite attacks. However, treatments may not always reach the center of the wood, so termites can still infest it5. To protect your home from termites, consider using termite-resistant materials such as Alaska yellow cedar, redwood, or Western red cedar6, and maintain at least 6 inches of clearance between wood and soil for easy inspection and detection of infestations7.

Pressure Treated Wood and Termites

Resistance Factors

Pressure-treated wood is an effective solution against termites, as it is chemically treated to provide termite resistance. The treatment involves infusing the wood with chemicals, such as borate, that act as a barrier against termites. Some of the factors that contribute to its resistance include:

  • Chemical treatment: The chemicals used in pressure-treated wood repel termites.
  • Extended lifespan: Compared to untreated wood, pressure-treated wood lasts longer.

Vulnerability Factors

However, pressure-treated wood is not entirely termite-proof. Some vulnerability factors are:

  • Age and decay: Over time, the chemical barrier can break down, making the wood susceptible to termite infestations.
  • Improper treatment: Insufficient or non-uniform chemical penetration can compromise the wood’s resistance.

Termite-Proofing Pressure-Treated Woods

To protect pressure-treated wood from termites, it’s essential to consider:

  • Regular inspections: Schedule termite inspections to identify any signs of termite activity.
  • Proper installation: Ensure wood-to-soil contact is minimized and that the wood is at least 6 inches above the soil.
  • Use of treated wood: Whenever possible, use treated wood in moist areas or those with higher risk of termite infestations.
FeaturesPressure-Treated WoodUntreated Wood
Termite resistanceHighLow
LifespanLongShort
Initial costSlightly more expensiveLess expensive
Maintenance (termite-wise)LowerHigher

By considering these factors and taking proper precautions, you can reduce the risk of termite infestations in pressure-treated wood.

Choosing the Right Wood for Termite Resistance

Naturally Resistant Woods

Some woods are naturally resistant to termite infestations. One example is teak, which has low termite survival rates. Other resistant species include:

  • Alaska yellow cedar
  • Eastern red cedar
  • Western red cedar
  • Redwood

These woods contain chemicals that repel or kill termites. However, they can be expensive, and availability may be limited.

Comparison Table:

Wood SpeciesTermite ResistanceAvailability
TeakHighLimited
AlaskanHighRare
HickoryMediumAvailable
CedarHighAvailable
RedwoodHighLimited

Alternative Building Materials

Apart from using naturally resistant woods, consideration can be given to other building materials. Pressure-treated wood, for example, is a popular choice due to its increased resistance against termites.

  • Pressure-treated wood: This wood undergoes a treatment process where chemicals are infused to increase its termite resistance. It is an effective option, especially for exterior-grade lumber.
  • Bamboo: Although not a traditional building material, bamboo is a sustainable alternative to traditional lumber. It is less likely to be targeted by termites compared to untreated softwoods like pine.
  • Composite materials: Manufactured materials, such as plywood or engineered wood products, are less attractive to termites and can be viable alternatives if properly used in construction.

Pros and Cons of Alternative Materials:

MaterialProsCons
Pressure-treated woodTermite resistantChemicals may leach
BambooSustainable and less attractive to termitesLess traditional
Composite MaterialsLess attractive to termitesMay require additional protection

Choosing the right wood or alternative materials for termite resistance is essential in preventing termite damage to homes and other structures. While naturally resistant woods offer excellent protection, alternative materials such as pressure-treated wood, bamboo, or composite materials can provide affordable and sustainable options.

Termite Control and Prevention Methods

Chemical Solutions

Chemical treatments are a common method to control termites. Homeowners can utilize termiticides, which are chemicals that target termite pests. Examples of termiticides include:

  • Fipronil
  • Imidacloprid
  • Permethrin

Pros:

  • Effective in killing termites
  • Long-lasting

Cons:

  • May harm beneficial insects
  • Requires a pest control specialist

Example: A homeowner discovers mud tubes near their home and hires a pest control specialist to apply chemical treatments.

Physical Barriers

Another way to safeguard homes against termites is using physical barriers. These barriers can prevent termites from making ground contact with the structure. Common physical barriers include:

  • Stainless steel mesh
  • Sand barriers
  • Crushed rocks
 Stainless Steel MeshSand BarriersCrushed Rocks
Prevents Ground ContactYesYesYes
Esthetic AppealLowMediumHigh
Installation DifficultyHighMediumLow

Example: A homeowner installs a stainless steel mesh barrier around their home’s foundation to deter termites from creating tunnels.

Proper Home Maintenance

Regular home maintenance is crucial in termite prevention. Homeowners should take precautions to minimize the risk of termite infestation. Some steps include:

  • Removing wood debris near the home
  • Repairing leaky pipes and faucets
  • Inspecting wooden structures for signs of termite damage

Pros:

  • Reduces risk of infestation
  • Promotes overall home health

Cons:

  • Requires ongoing effort
  • May not completely prevent termites

Example: A homeowner seals any gaps and cracks in their home’s foundation and removes unnecessary wooden materials from their yard to discourage termites.

Dealing with Termite Damage

Identifying Structural Damage

Termites can cause significant structural damage to buildings, feeding on cellulose found in wood, plants, and paper products. Some signs of termite infestations include:

  • Cracks in wood or floor
  • Damaged particle board
  • Hollow-sounding wood

Keep an eye out for damp areas and mold, as these can provide ideal conditions for termites to thrive.

Repair and Restoration Options

When faced with termite damage, some restoration options include:

  • Sealing cracks
  • Replacing damaged wood
  • Installing insulation to prevent dampness

For minor infestations, boric acid or sodium borate can be applied to the affected areas. However, this treatment might not be suitable for all situations due to toxic chemicals associated with it.

Professional Assistance

It’s recommended to seek professional help for more severe termite infestations and structural damage. Pest control companies like Terminix can offer specialized treatments and repairs for your property. They may use liquid termiticides or physical barriers depending on the severity of the infestation and the type of termite involved.

Here’s a comparison of do-it-yourself and professional termite control methods:

DIY Termite ControlProfessional Termite Control
Lower costBetter effectiveness
Limited to minor damagesComprehensive for severe damage
Chemical handling riskSafe and regulated chemicals
Limited expertiseSpecialized knowledge

When selecting a termite control method, it’s important to consider the pros and cons of DIY approaches versus professional assistance to ensure effective and long-lasting results.

Footnotes

  1. https://edis.ifas.ufl.edu/publication/IG098

  2. https://hgic.clemson.edu/factsheet/drywood-termites/

  3. https://hgic.clemson.edu/factsheet/drywood-termites/

  4. https://agresearchmag.ars.usda.gov/2015/nov/termites

  5. https://extension.msstate.edu/content/methods-termite-control

  6. https://basc.pnnl.gov/resource-guides/termite-resistant-foundations-and-walls

  7. https://extension.msstate.edu/content/methods-termite-control

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Pacific Coast Dampwood Termites

Possible Beetle?
Location:  Northern California
September 25, 2010 3:33 pm
Hi Bugman,
We found these buggers yesterday on a redwood overhang outside our house located on the San Francisco peninsula, California. We’re having especially warm weather right now — a slow transition into fall. They seem to have 6 legs and 2 antennae, a dark brown or black lower half, with a reddish brown head. They are about 7-8 mm in body length.
Thanks for your help!!
Signature:  Hal

Pacific Coast Dampwood Termite

Hi Hal,
This sure looks like a Pacific Coast Dampwood Termite,
Zootermopsis angusticollis, to us.  Try comparing your image to this image on BugGuide.

Letter 2 – Pacific Dampwood Termite: Soldier

Drywood termite larvae?
Hi Lisa and Daniel,
With your help I identified some nasty larvae that had fallen from my wood beamed ceiling. I already had strong evidence of dry wood termites. I live in Playas de Rosarito, Mexico 20 minutes from San Diego on the beach. The humidity is very high. The homeowners here have predilection for wood vaulted ceilings. That is why I have not called an exterminator when every morning I see wooden droppings. At the beginning I thought these were grains of sand carried from the beach, but were not. My reasoning for not calling an exterminator was not because of mercy, I thought that when the house would not be toxic any longer (from the exterminators tent) and I would be able to comeback, the termites will be back as well either from the neighbors wood beamed ceilings or because of the environmental conditions. This morning, among the digested particles of my beautiful ceiling there were these very ugly crawling little beasts that resembled silverfish, but I noticed that the powerful jaws (seen on the picture), were not in the tail but in the front when they took their walking baby steps on my floor. I am sending you the picture; very similar to the one you have but this one show the jaws. Great site you have. I seen a website one time on how to kill dry wood termites naturally by introducing a worm like predator. Not very appealing but better than getting poisoned together with the termites. Could you ask your expert sources about it? I forgot the name of the worm and the site. Thanks
Celia

Hi Celia,
It is our belief that this is actually a Soldier caste from a different species, the Pacific Dampwood Termite, Zootermopsis angusticollis. This is a larger termite and it will eat all types of wood, but is most commonly found in buried wood that is subject to moisture. Hogue notes: “By vibrating their heads on the walls of their chambers, soldiers and nymphs produce an audible ticking sound that is believed to function as an alarm to the colony.” We don’t know about the parasite you mentioned.

Letter 3 – Rottenwood Termites, we think

Second Floor Termite
April 2, 2010
In October and November of last year, we had flying termites swarming in the second floor of the house. They seemed to be coming out of a damaged (eaten) area of the floor near some “patio” doors that used to lead out to a deck that had been removed in 2007. Today, a contractor opened the stucco and found a lot of damage along with some living bugs shown in the pictures. They looked a bit more whitish to us than they appear in the photos.
Joe and Joan
On Twin Peaks in San Francisco

Termites

Hi Joe and Joan,
Our best guess is that you have Rottenwood Termites in the family Thermopsidae based on the possibilities on BugGuide, though that is just a guess.  Thanks for providing our readership with valuable images of Termites.

Termites

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

4 thoughts on “Do Termites Eat Pressure Treated Wood? Unveiling Their Appetite”

  1. I live in N. Ca. and recently found a couple of strange critters on our stove. 2 yrs. ago our rental was fumigated for a bad infestation of subterranean termites. My husband took a picture of this new critter. Is there a way that I can get the photo to you for ID? Thanks.

    Reply
  2. Hello – came across this old post and wonder if you were able to identify these bugs? WE are in the same area and just found the same things on our redwood arbor. The inspector said they were not termites though.

    Reply

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