Among the many natural threats homeowners face is termite infestation. Precautions can minimize that threat.

Two major types of termites live in Louisiana, according to LSU AgCenter entomologist Dr. Dennis Ring. One is the subterranean, and the other is drywood. Subterranean species are a more common threat to homeowners because they have much larger colonies. Subterranean termites need a source of water, often the soil. Drywood termites do not need a moisture source.

The Formosan subterranean termite has received the most attention in recent years because of the extensive damage this non-native, invasive species has done to the many parts of Louisiana, most notably the New Orleans French Quarter, site of the national termite control program Operation Full Stop.

The subterranean termites usually start colonies in the soil, require moisture, build mud tubes to access aboveground wood and bring soil into the wood they infest. Most prefer to eat wood along the grain, Ring explains.

Formosan termites enter a house primarily by constructing shelter tubes to protect themselves as they migrate from the soil to the house.

To prevent entry, apply a chemical barrier to all possible entry points, advises LSU AgCenter Formosan termite expert Dr. Gregg Henderson. He explains that the termites would then have to cross a poison barrier to enter the structure.

"Unfortunately, a number of factors can prevent a perfect treatment," Henderson adds. For example, the type of construction can make a difference. Louisiana homes typically are built on slabs or piers.

Termites cannot eat through a solid concrete slab, but they can come up around the outside edges or enter through some other opening in the slab. That is why traditional termite treatments require the application of a continuous chemical barrier to the soil around all possible entry points.

Raised houses can be some of the easiest to protect against Formosan subterranean termites, according to Henderson. To infest a raised structure, the termites must travel up or through the piers or any other objects connecting the building with the ground.

Since the underside of the structure is completely accessible for inspection, termite infestations can be detected before serious damage has occurred.

"Often, infestations of pier houses can be traced to one of only a few common entry points," Henderson says.

Homeowners and landscapers may unwittingly contribute to the spread of termites, according to Ring. Termites can be found in railroad ties, utility poles, wood from structures, lumber, pallets, landscape timbers, wood used in the oil industry, firewood, trees, woody plants, sawdust, mulch, wood in boats, potted plants, mobile homes, homes and paper.

To determine if material is infested, Ring says to make a thorough inspection, looking for damaged wood, soil, mud tubes, a carton nest and the insects themselves. Infrared photography may be used to help determine if the inside of wood is infested.

"Soil or concrete, above the level of the slab, can be one of the worst things that a homeowner can do to attract subterranean termites," Henderson says. If the soil level is too high, the termites can move straight into the house without being detected. In this case, the homeowner will not know termites are present until parts of the house have been eaten away.

In addition to facilitating termite infestation, above-grade soil can lead to costly water damage. If you leave at least 4 inches of clearance between the brick or siding and the soil, you will be able to see these tubes during casual inspections.

Like with many things, early detection is critical when dealing with Formosan subterranean termites. If the termites are discovered early enough, they can easily be eliminated before they can cause major damage, the AgCenter scientists say.

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Contacts:
Gregg Henderson (225) 578-1831 or GRHenderson@agcenter.lsu.edu 
Dennis Ring (225) 578-4615 or Dring@agcenter.lsu.edu
Writer:    
Mark Claesgens (225) 578-2939 or mclaesgens@agcenter.lsu.edu