Where Did The Termites Come From?

Never say never and never say always. Many of you who know me are aware that is one of my favorite maxims when talking about what insects can do. Just when you think you have seen it all with a group of bugs, they will do something to surprise you.

One situation I am often presented with deals with termites that are found in newly purchased garden soil or mulch. Homeowners will often accuse garden centers and similar outlets of selling them soil or mulch loaded with termites and in some cases request that the supplier pay for a termite treatment at their property. The suppliers of the soil or mulch usually pushes back, saying termites could not be in the materials because of the mixing, grinding, screening, blending or other disruptive processes they use to prepare and/or amend the products they sell.

at a property move into newly applied soil or mulch? Yes.
So then, which is more likely?

For a quick primer, remember that subterranean termites are common throughout South Carolina and the entire southeastern U.S. While they are pests when they damage our structures, most termite colonies are beneficial in the environment, recycling wood and other forms of cellulose back into basic nutrients that are important for the environment.

Typically, a mated subterranean termite queen lives underground in a chamber where she lays eggs. In South Carolina, we have 3 common native subterranean termites.  A queen may live for 10 to 20 years. When the eggs hatch, most of the young termites become workers, foraging for wood that the termites eat. The number of termites in a colony will vary, but based on mark-recapture work done in our lab and other local labs over the years, the average number of workers in a mature native subterranean colony is probably between 80,000 to 100,000. For a colony to function and survive, termites need their queen/reproductive termites and a stable environment where they can forage for wood.

In a study done at North Carolina State University in the Raleigh area, researchers used genetic techniques to determine different subterranean termite colonies in residential neighborhoods. They found an average of 25 different subterranean termite colonies per acre in yards around the homes, with a high of 75 different colonies in one acre (Parman and Vargo, J. Econ. Entomol. 101 (4): 1349-1359 (2008)).  That same study found termite foraging distance and area covered can vary widely depending on the termite species and conditions, but most termite workers in their study foraged approximately 7 to 53 feet and they found a native colony may encompass an area of soil from 33 to 890 square feet.

In our region of the country, this research indicates that termite colony numbers are high and ubiquitous almost anywhere there is soil and wood for termites to consume. Thus, most yards and properties in the Carolinas would have high termite numbers already established. We just don’t see them because they tend to be hidden underground or in wood.

Garden soil or mulch from a facility where components may be frequently added, mixed, screened, ground, and/or blended would not be conducive for termite colonies foraging for wood, living and surviving. With all the disturbances, it is not likely that termite colonies could be established. It is more likely that when new soil or mulch is added to a property, termites already established at the property move into the added material, and not vice versa.