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| Termite Resistant Structures |
Pressure-Treated Southern Pine Takes the Bite out of Formosan Termites
The concept of using treated wood framing components in high-moisture areas
of the home for added protection against decay and termite attack is nothing
new. The concept of using “Whole House” treated wood framing is an idea
whose time has come, necessitated by a relatively new immigrant predator: the
Formosan subterranean termite.
The Formosan subterranean termite is one of some 2,400
known termite species in the world. Originally a native of
mainland China, the Formosan termite is believed to have been
introduced to the continental United States by the military in
packing crates shipped from the Pacific after World War II into
New Orleans and a handful of other Southern ports. Today,
Formosan termites can now be found in 8 Southern states, California
and Hawaii and are expected to continue
spreading northward as far as Washington State on the west
coast and Massachusetts on the east coast.
Despite its innocuous appearance, this "super termite" as it
has been called is, in fact, the most pervasive, aggressive, and
destructive breed of termite in the world. Native subterranean
termites pale in comparison to this voracious breed. In comparing
native subterraneans to Formosan termites, it is easy to see why the Formosan termite has been
labeled the perfect living eating machine of the termite world,
and why they are so hard to control.
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Native Subterranean Termite |
Formosan Termite |
AVERAGE
COLONY SIZE |
100,000 up to 1 million. |
Ten million or more. The largest known single Formosan termite
colony found in a public library building in Algiers, Louisiana exceeded 70 million. |
| AGRESSIVENESS |
Moderately aggressive; a typical colony will consume about
7 pounds of wood per year. Termite shields (properly installed)
are reasonably effective in helping to control. Percentage of
soldiers in a typical colony is less than 2%, making them
somewhat vulnerable to outside predators like ants. |
Extremely aggressive; a typical colony will consume over 1,000
pounds of wood per year. Termite shields are less effective.
Formosan subterranean termites will go through thin sheets of
metal, mortar, PVC pipe, electric power lines and telecommuni-cations
lines to get to wood or cellulosic material. This termite
will eat wood, paper, books, furniture — anything cellulosic. A
typical colony has 10% to 20% soldiers and therefore is much
less vulnerable to outside natural predators. |
| ADAPTABILITY |
Moderately adaptable; more limited range; species is ground-dependent
for water, making it easier to detect via mud tubes
and (if present) in the structure, usually at first-floor level.
Prefers wet dead wood. Will not ordinarily infest living trees. |
Extremely adaptable; not ground-dependent for moisture; can
live off water condensation even at attic level. Builds carton
nests in walls and roofs; carton nest serves as a satellite home,
trapping and conserving water. Very difficult to detect in closed
structures until severe damage has been done. Also attacks and
causes severe damage in a broad species range of living trees;
they prefer hardwoods like oak, gum and maple, but will attack
softwoods including Southern Pine. Much more adaptable to
varying soil types, climates, and settings — urban to the wild. |
| MOBILITY |
Moderate to low; ground dependent; and relatively weak flyers in
the alate (flying stage) form. |
Very mobile; move around extensively when disturbed; not
ground dependent. Alates are proportionately stronger flyers. |
REACTION
TO CHEMICAL
TREATMENT |
Susceptible to most chemical treatments. Ground-line treatments
are moderately effective in combination with good home
preventive maintenance. |
There is good evidence that Formosan termites are more
resistant to several of the contact chemicals used in treatment.
Ground-line treatments are ineffective in controlling Formosan
termites, the insect will go over, around, or simply avoid the
treatment area while seeking a food source. |
CONCLUSIONS: It is estimated that replacing wood damaged by all
types of termites is in excess of $2 billion per year in the United States.
The Formosan subterranean termite is now believed to be the cause of
over half of this damage ($1.2 billion per year) in spite of being inadvertently
introduced by way of U.S. Southern ports less than 50 years
ago. In the greater New Orleans area, which is indisputably the hardest
hit metropolitan city in the continental United States, the annual
damage is estimated to be $300 million to $500 million and is
increasing dramatically every year.
Entomologists agree that efforts must be undertaken to regain
control of the Formosan termite and limit their damage in the hardest-hit
buildings. Scientists simply state that we must stop building
"termite food" homes with little or no preventative measures within the
range of this pervasive insect.
One of the principal control measures that can be used to protect
the structural framework of buildings is to use preservative-treated
Southern Pine lumber and other engineered wood products in new
home construction and remodeling projects. |
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