The Terrible Termites

Formosan Subterranean Termites cost Hawaii residents about $100 million a year.[1] Across the U.S., estimates place the damage from termites at over $5B/year. Due to its size and aggressive foraging behavior, a colony of Formosan termites does more damage than single colonies of other U.S. subterranean species, and can cause significant structural damage to a home in only 6 months.

They are known to enter buildings through cracks in concrete flooring or travel under tile flooring through gaps less than 1/16" wide[2]. They have also been known to eat their way through concrete, bricks or mortar to reach wood, chewing through many other materials, including insulation around underground electrical lines causing power outages. FSTs can eat through thin sheets of metal, mortar, PVC pipe, electric power and telecommunication lines and most woods, including hardwoods, paint, plaster, gypsum board, and even CMU block in order to get to a food source. A typical colony will consume over 1,000 pounds of wood per year[3]

Unpredictable invasiveness of ground termites makes them difficult to detect and control[4].

The termite is ‘hidden from view’ at all times. The presence of termites may be indicated by: a sagging door or floor, leaks in the roof, a warped wall, a hollow sounding beam, discolored or blistered paint, depressions in wood, moisture collecting in unusual places, springy floors or steps, mud tubes on interior or exterior walls, wood rot, interruptions in power or communications like short circuits, telecommunication blackouts, or similar problems. By the time termites are detected, considerable damage has already been done to the structure.

FSTs can travel from below ground to a suitable food source as high as the third story attic space, and higher. [5] Formosan termites can establish secondary colonies in very moist wood of upper stories of buildings (even several stories above ground) and do not need soil contact if there is a nearly constant moisture source.  This is particularly prevalent in areas of high humidity where wood moisture is above average. Leaking roofs or plumbing fixtures are common water sources for such “aerial” colonies.[6]

It has been documented where a mud tube was built from the wood floor, up over 12” into the air to reach a water source: water in a waterbed.  The termites actually reached the wood frame of the bed and ate through the wood to get to the water source.  The discovery was made only after the bed leaked.[7] Ground termites eat mainly the springwood (softer wood) of susceptible timbers, most often leaving the summer wood (harder wood) sections. This can be easily seen when a damaged timber is cut open for inspection. 

Trees serve as gateways for termites to enter a house. Termites constantly search for food sources, which include trees. There are a number of cases in Hawaii where live plants and trees have been attacked by termites. Termites infest the center of a tree but do not break through the bark. They eat right up to the outer rim of the tree. The tree can be weakened considerably so that when a strong wind comes along it can fall over. The danger in having an infested tree in the yard is that ground termites can travel through the roots. If the roots go under the foundation of the house it is a subway that can lead them into the house, where the structural wood becomes food. Because they travel inside the root and are afforded its protection they can be very difficult to control or detect. Among the termite favorites are papaya, sweet corn, mango, avocado, various citrus, Norfolk pine, and eucalyptus.  Most houses built in the 80s were constructed on agricultural lands that had been infested previously by termites.

In Hawaii, when a home is found by pest control companies to be infested with Drywood termites (not yet with subterranean termites), that usually means tenting the home. Tenting a home is a process where the house is covered with a tent or tarp. Gas is pumped into the home and left alone for at least 24 hours to kill the termites. The gas is then released from the home and inspectors come in to measure the gas in the air to make sure it is safe to re-enter the home. House tenting is costly. The occupants must vacate the home for 2-3 days including all pets. An increase in house break-ins has been observed the past few years as the tenting provides an open invitation to vandals that the homeowner is not present. This is not a practice commonly used with subterranean termites

(From Treated Wood Use in Hawaii, December 2009)


[1] In 1990, annual figures for prevention, control, and repair were conservatively estimated at $60 million. By 1996, that figure had grown to over $100 million per year.

[2] Formosan Subterranean Termites. January 1995. A Consumer Guide to Termites and Termite Control.

[3] Southern Forest Products Association. Pressure-Treated Southern Pine Takes the Bite out of Formosan Termites.

[4] Yates, Julia R. and Tamashiro, M.  The Formosan Subterranean Termite in Hawaii. Publication No. HSP-2, Cooperative Extension Service, College of Tropical Agriculture and Human Resources (CTAHR) University of Hawaii at Manoa, Honolulu, Hawaii, February, 1999.

[5]  Grace, J. K., R. J. Woodrow, and J. R. Yates. 2002.  Distribution and management of termites in Hawaii.  Sociobiology 40:  87-93.

[6] Woodrow, R. J. Grace  J. K., and Yates III, J. R.. 1999.Hawaii’s Termites – An Identification Guide. Publication No. HSP-1, Cooperative Extension Service, College of Tropical Agriculture and Human Resources (CTAHR), University of Hawaii at Manoa, Honolulu, Hawaii, February 1999. P. 1.

[7]  This particular case happened in Halawa area near Aiea.