[Technically Speaking] Subterranean Termites — the Real Story

Recently, I have heard radio advertising in our area that goes something like this, “Termites eat one pound of wood per day.” In my opinion, this information serves only one purpose — to put fear in the hearts of homeowners and prompt them to call the “pest management professionals” and “QualityPros” that are promulgating this misinformation. What’s the real story?

One of the less onerous items of misinformation used by the industry occurs when companies pass out door hangers or go door to door in a neighborhood informing homeowners that their neighbor’s house was treated for termites. On the surface, this is not so bad — unless the implication is that because a neighbor has termites you surely do or will and should treat immediately to protect your investment. What’s the real story?

This article will present some of the most recent research and information that will allow you to better understand the habits and behavior of termites and to debunk this misinformation. The following information comes from published information by the most notable termite researchers today, e.g., Brian Forschler, Ken Grace, Michael Haverty, Gregg Henderson, Susan Jones, Faith Oi, Michael Potter, Rudy Scheffrahn, Nan-Yao Su, Barbara Thorne and Lonnie Williams.

COLONIES. Termite colonies are best described as “decentralized entities occupying multiple nesting or foraging sites interconnected by an extensive network of underground tunnels” or “a group of termites sharing interconnected foraging sites.” Defining a termite colony lays the groundwork for understanding how different factors affect its habits and behavior.
Temperature and moisture have the most dramatic effects on the colony. Note that:

• Death readily occurs at temperatures more than 100° F and at temperatures less than 25° F.
• The optimal temperature range is 75° F to 95° F.
• Moisture-saturated soil, e.g., flooding, results in death.
• Termites readily survive in wood with wood moisture content (WMC) of more than 20 percent.
• To survive extremes in temperature, termites readily burrow down 40 inches and can readily survive above-grade in structures if moisture is available (aerial colonies).

In addition to these factors, the availability of food, soil type and compaction impacts colony size and foraging. Studies on colony size vary based on the area of the country. For instance:

• Mississippi — 51,000 to 363,000 individual termites per colony
• Florida — 200,000 to 5,000,000 individual termites per colony
• Toronto — 720,000 to 3,200,000 individual termites per colony
• Georgia — 55,000 individual termites per colony

Termite colonies don’t reach this size overnight; even under ideal conditions it takes years for colonies to mature and swarming to occur. Colonies originating from a founding king and queen begin their first year with only 50 individuals; by the second year, the numbers average 387 (range 51 to 984). Typically, swarming doesn’t occur until the third or fourth year, unless the structure is built directly over the colony.

TUBES. Exposed worker termites are very susceptible to environmental conditions. If they are not traveling through wood, foam or some other protective envelope, they must build tubes. Tubes conserve moisture and protect termites from predators; they don’t block out sunlight or conduct moisture from the ground to wood.

Tubes are composed of soil, wood, debris and/or feces. Tubes serve many functions, e.g., exploratory (narrow, branching and fragile), working (larger and more substantial), drop (downward from wood to reestablish contact with the ground) and swarming. Workers can build tubes at the rate of several inches per 24 hours. They rebuild tubes three times faster than they construct tubes, i.e., broken tubing is built at a rate of 1.2 inches per 65 minutes.

Underground foraging tubes follow pipes, roots, expansion joints and other natural and man-made features. Above-ground foraging tubes commonly are found along foundation joints, sill plates, joists, between double joists and other structural elements. Foraging activity is affected by temperature, moisture gradients, chemical odor (decaying wood), and soil composition; termites don’t sense wood. Foraging territories can change size in weeks or months.

Foraging occurs throughout a network of tunnels and it is not random. When termites forage through a small portion of their territory and discover a food source, the foraging takes on a distinctive pattern, i.e., the spokes of a wheel. The activity radiates out from the food source until another food source is located and the pattern repeats itself. Once a food source is located, the workers shift their activity pattern from “search mode” to “highway mode.”

WOOD. Termites exhibit distinctive preferences for wood:

• They prefer slash and loblolly pine more than Douglas fir and ponderosa pine
• They prefer softwood to hardwood
• They prefer fungus-decayed wood to sound wood
• They prefer moist wood to dry wood

Wood consumption measured in the laboratory under ideal environmental conditions has indicated the following:

• If no food alternatives were present,
  o 1,000 termites ate 83 milligrams of wood per day.
  o 60,000 termites ate 0.2 ounces per day.
  o That is the equivalent of 1 foot of a 2-by-4 board eaten in 157 days.
• If no food alternatives were present,
  o 100,000 termites ate 5 inches of a 2-by-4 board per year.

FINAL THOUGHTS. The researchers named at the beginning of this article have advanced our knowledge of termites dramatically in the past 20 years. Despite this, we still have a lot to learn. One thing we don’t need is misinformation clouding and misrepresenting the sound science.

Are the two claims at the beginning of this article factual or are they just marketing hype designed to intimidate prospective customers? You be the judge.

The author is president of Innovative Pest Management, Brookeville, Md. He can be reached at 301/570-3900.