Termites in mulch : Danger of using mulch close to your house

Wood mulch and stone mulch can create termite problems

By Sandy Feather
Penn State Extension

Q. A friend told me not to put mulch next to the foundation of my house since it can lead to a termite problem. Does wood mulch attract termites? Are stone mulches safer to use in place of shredded mulch?

A. Termites – also known as subterranean termites – are soil-dwelling insects that require even soil moisture and protection from temperature extremes to thrive. You may be surprised to learn that pea gravel and river rock used as mulch near buildings are just as likely to support termites as wood-based mulches. Although termites sometimes feed on wood mulch, it is not a preferred food source because it has low nutritional value for them.

It’s not just wood mulch for termites!

Mulch of all kinds can create a perfect environment for termite activity because it helps maintain soil moisture and moderates soil temperatures. Since moisture is the main attractant, the type of wood mulch used makes no difference. The amount of mulch is a more important factor.

Stone mulches can also contribute to termite problems since they help keep the soil evenly moist.
Stone mulches can also contribute to termite problems
since they help keep the soil evenly moist.

A two-inch layer of mulch is sufficient to obtain its benefits for plants – maintaining soil moisture, moderating soil temperatures, and keeping weeds down. Wood-based mulches have the added benefit of adding organic matter to the soil as they break down. Mulch becomes a problem when we use too much of it, because the underlying soil never gets a chance to dry out, which increases its attractiveness to termites looking for a place to call home.

People who add a few inches of fresh mulch every year so that it looks nice can easily wind up with excessively thick layers of mulch around their plants and near their houses. In addition to creating a perfect environment for termites, excessive mulch around plants is not good for them, either. A better approach is to rake out the existing mulch and only add fresh mulch in places where there is less than two inches. Properly used wood mulch is so beneficial to plants that fear of termites should not preclude its use in the landscape.

Keep your Distance

To minimize problems with mulch and termites, never allow any kind of mulch to physically contact a structure. Keep plants three – four feet away from the foundation to increase air circulation so that the soil has the opportunity to dry. It is also important to make sure that the soil around the foundation is sloped away from the structure so that water drains away from the foundation rather than toward it. Make sure that gutters and downspouts are working properly so that runoff is directed away from the foundation. Adjust sprinklers and irrigation systems so that irrigation water does not puddle near the foundation.

How to tell a Termite from a Winged Ant

Antennae: Straight.
Wings: 4 wings are all the same length and almost twice as long as the body.
Waist: Broad, thick.


Antennae: L-shaped.
Wings: 4 wings vary in length and are about the same length as the body.
Waist: Narrow, wasp-like.

Avoid piling lumber or firewood next to a structure, which could provide an easy route for termites into the building. It is also important that any wooden parts of a structure are at least six inches above the soil. Even treated wood can be damaged by termites because they can exploit tiny cracks and crevices to get into the center of the piece, where the treatment may not penetrate.

Old piles of firewood close to your house
may attract destructive carpenter ants and termites

If you see signs of termite activity, including the mud tubes termites build to get from place to place, damaged wood that has been hollowed out along the grain, or if you see a swarm of winged termites or evidence they have swarmed in your house such as shed wings, contact an exterminator. Termites can be tough to manage, and materials available to homeowners may not provide sufficient control.

Get at least three estimates for pest control work, and do not be bullied into choosing a company quickly. Although they are damaging, termites will not bring your house down overnight. Make sure the company you choose has insurance, proper pesticide licensing, and that they guarantee their termite treatments.

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