Drywood or Subterranean Termites – Differences
by Brian Mase
Termite colonies can contain thousands to millions of termites that work 24/7 boring their way into and through all manner of wood structures, including homes, garages, sheds, and furniture. Every part of a New England home, from just above the foundation to the roof decking, is in danger of being structurally weakened or destroyed when a termite infestation takes hold.
But it is not enough to know that termites have invaded your premises. Unless you identify which type of termites you are dealing with, there will be no way to know which extermination methods will be most effective.
Below, we introduce you to the basic facts about the two major types of termites that inhabit the United States: Drywood or Subterranean Termites, why should I care?
By far the most common type of termites in New England and throughout most of the U.S. are subterranean species. The winged “swarmers” that you may see during termite breeding season are generally black with subterranean termites but red with dry wood termites. Both types of termites also have “soldiers” with enlarged mandibles, but only subterranean species have a distinct worker caste, which is white and wingless.
Subterranean termites typically become a problem when they live in the soil of nearby homes, businesses, or other wood-containing structures. The termites tunnel their way to the base of the building, construct mud tunnels to food sources within the building, and rapidly consume the cellulose found in wood.
Termites out “on excursion” then bring back food to the nests, which must remain in or on the soil and in a place that is relatively moist. Infestations usually consist of a single, large colony, which takes two to four years to fully mature.
Eliminating subterranean termite infestations can be accomplished by two main methods:
- Liquid repellent termiticide: This method kills termites immediately upon contact and is designed to protect wood structures.
Liquid non-repellent termiticide: This is a delayed-action method that allows the termites to share the poison with the colony before they succumb to it themselves.
With subterranean termites, termiticides will often be planted in trenches surrounding the house or infested area. Sometimes, it may also be foamed into the walls or injected under the foundation through drill holes.
While 90% of U.S. termite infestations involve the subterranean variety, dry wood termites are common along the Gulf Coast and in Southern California. Their full range stretches along the coast from southern Virginia, past Florida, through Texas and Arizona, and up into Central California.
New Englanders may think they are safe, therefore, from dry wood termites, but this is not necessarily so since they often ride inside of furniture to places far outside their normal range.
Drywood termites have smaller nests, but they also reproduce faster. And it is common to find multiple colonies simultaneously working on consuming the same house. Drywood termites are also able to live
away from the soil and with minimal moisture. In fact, their nests are formed inside of the wood they consume.
Signs of a dry wood termite infestation include:
- Deposits of “frass,” which is a distinctively shaped termite dropping. Frass consists of hard pellets with six concave sides and rounded ends.
Tunnels that, unlike with subterranean termites, cut across the grain of the wood.
Small, brownish “plugs” over eighth to quarter inch diameter openings in the infested wood.
The best extermination method for dry wood species of termites is fumigation. This can be a whole building in extreme cases (this almost always kills 100% of the termites) or spot fumigation inside infested wood, where the problem is less widespread.
Professional Termite Control
It is not always easy to distinguish dry wood from subterranean termites or even termites from winged ants. And even when you are sure of the “culprit” and have thoroughly investigated the damage, it is often best to rely on the superior methods of professional termite exterminators to ensure identification success and to avoid a quick re-infestation.
“Drywood or Subterranean Termites”, by Brian Mase