The most common type of termite in North America is the subterranean termite. These termites are native to underground areas as they are sensitive to heat and low humidity. Soil offers protection from heat and low humidity. Termites are found in most of the United States and Mexico, but are not very common in Canada. Subterranean termites will readily enter structures but must normally protect themselves from predators, heat, and low humidity. In order to do this, they build mud tubes or shelter tubes, composed of soil material and water to protect the sensitive workers from adverse conditions. The most common types of subterranean termites are the native subterranean termite and the Formosan termite, Coptotermes formosanus.
The native subterranean termite is indigenous to the continent and is the most common type of termite found in North America. The population of these termites in a particular colony can exceed a million insects. The Formosan termite, imported accidentally from Asia in the 1900s, can have larger populations, and is more voracious in terms of wood damage. Termites cause over five billion dollars in damage each year and the Formosan termite has wreaked havoc on the French Quarter in New Orleans, preferring tropical and subtropical climates.
Drywood termites live entirely within dry wood, have small colonies containing a few thousand individuals. Thus, it takes a long time before drywood termites cause much damage. Structures may be infested with drywood termites for years without being noticed. Drywood termites disperse naturally through alates that take flight. Shipment of infested wood or furniture may relocate entire colonies or nests.
Drywood termites are typical of very warm climates and do not need soil contact. These termites are commonly found in south Florida, southern California, and Hawaii.
Subterranean termites usually make their nests in the ground, excavate passageways connecting nests and tunnel though the soil in search of moisture and food. They break into houses through construction elements such as expansion joints, hollow bricks, crevices in walls, support structures, concrete slabs, plumbing and utility penetrations, under exterior facings such as stucco and wooden siding via openings as small as 1/32 of an inch. They build mud tubes (shelter tubes) to reach aboveground wood and are capable of establishing isolated aboveground infestations in buildings where they have access to water from condensation, leaking pipes, roofs or other sources. Subterranean termites have large colonies ranging from hundreds of thousands to millions. Termites from a single colony may attack more than one structure. They cause serious damage much faster than drywood termites. Subterranean termites feed on dead wood, and often injure living trees and shrubs. They also show a tendency to injure vegetables in dry seasons. Subterranean termites disperse naturally through foraging movements of workers and soldiers and by the flight of alates.
Native subterranean termites have colonies ranging up to several hundred thousand termites and forage territories up to 1/3 acre. The foraging distance from the colony may be over 200 feet. They may be found injuring living trees, but usually feed on dead tissues.
Formosan subterranean termites eat wood much faster than native subterranean termites and grow the largest colonies of any termite species in North America. A mature colony has up to 10 million termites or more and may extend passageways 10 feet deep underground and over 1/2 acre in area. Formosan subterranean termites are more likely than native subterranean termites to survive in a structure without ground contact. They are also more likely than native subterranean termites to injure living plants. Although an infested tree is not usually killed by Formosan subterranean termites, the injury weakens the trunk, branches and roots, making them susceptible to breakage during high winds.
To reach cellulosic materials or a water source, Formosan subterranean termites will chew through and destroy many non-cellulosic materials, such as thin sheets of soft metal, electric lines, plastics, mortar, plaster, rubber insulation, stucco, neoprene and seals on water lines.
Treatments for Termites
Control for termites can be accomplished by soil treatments, wood treatment, and baits for subterranean termites, as well as fumigation and wood treatments for drywood termites.
The goal of termite integrated pest management is to prevent or reduce problems caused by termites. There are several options for treating an existing structure for termites.
Qualified pest control operators should be consulted for options to be used because treatments vary according to termite species, degree of damage, building construction, environmental conditions, etc. Since proper treatment includes the use of specialized equipment, large quantities of diluted insecticide and frequently involves drilling concrete foundations, bricks or walls, it is not recommended that untrained people attempt to treat a structure for termites.
Application of Termiticides – Soil Treatment
This is the standard practice for treating a structure. A termiticide is placed into the soil under and around a structure to create a continuous chemical barrier which blocks potential routes of termite entry. A trench at least 4-inches wide by 6-inches deep is dug around slabs, piers or other supports touching the soil. The soil put in the trench is saturated with termiticides. Any material that has a void and touches the soil must be drilled and the void treated with termiticide. Currently labeled soil termiticides will protect a structure for approximately five years. Wood treatment can be used either as a preventive measure or for the treatment of termite-infested wood. Termiticide foams have been used recently as a way of improving chemical barriers, especially in callback situations (a return call on a customer to give re-treatment service on a treated house). Termiticide foams are very useful in treating structural voids by providing a full surface cover of the voids.
The Bait system
This is a new technology for treating subterranean termites. Two types of stations have been used.
In-ground bait stations are placed around a house in the soil. Generally, monitoring stations are installed first and inspected several times a year for signs of termite activity. Monitoring stations contain a cellulosic material, such as wood or cardboard. After termites are found in the station, the cellulosic material is replaced by termiticide-treated cellulosic material. Aboveground stations are placed on walls and floors directly or adjacent to termite activity or infestation. Termite baits work by killing workers that eat the toxin directly or termites that have shared the toxic food with workers or by eating intoxicated termites. Thus, colonies can be reduced. There are no attractants other than cellulose in the baits.
In this process, structures are covered with a tent and a lethal gas is released into the structure. This treatment kills termites in the structure, but not termites in the soil. It is effective in killing drywood termites as they infest and live self-contained in the wood in a structure. It is not recommended without other treatments for controlling subterranean termites because termites in the soil may re-enter the structure as soon as 24 hours after fumigation.
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- Termite Facts
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