Among the wood destroying insects in the United States, subterranean termites are the most destructive pests. They cause more than $2 billion in damage each year, more property damage than fire and windstorm combined.
Subterranean termites are beneficial in nature, as they break down many dead trees and other wood materials that would otherwise accumulate, recycling them to the soil as humus. Problems, however, occur when termites attack the wooden elements of buildings, especially sine their presence is not readily noticed. Subterranean termites hide their activity behind wallboards, siding or wood trim.
Subterranean Termites Distribution, Biology and Habits
There are several species of subterranean termites in the United States, found in every state except Alaska. Two major types of termites are most common and seriously threaten wooden structures:
- the Reticulitermes genera of termites is found throughout the state, decreasing in frequency from the Gulf Coast to the central regions
- the introduced Formosan subterranean termites, generally found in the Houston Ship Channel area down to and including Galveston and Texas, and the Beaumont-Port Arthur-Orange area. Termites are easily transported in timber, especially landscaping timbers.
Subterranean termites live in a nest or termite colony in the soil. These colonies are made up of three castes: reproductives, workers and soldiers, with several stages for individuals of each cast – the egg, the larva that develops in a pseudo-stage and eventually into a brachypterous or soldier, and the adult. Reproductive adults have three forms: primary, secondary and tertiary reproductives.
Biology and habits
A termite colony matures in two to four years, after which swarmers are produced. Swarming usually occurs from January through April, during the daylight hours, typically after rain. The emergence of swarmers can also be triggered by environmental factors such as heat, light and moisture. Each species has a definite set of conditions under which it swarms, and the number of swarmers produced is proportionate to the age and size of the termite colony. Both male and female swarmers fly from the colony, but they are extremely weak fliers and only a small percentage survive to develop colonies.
The size of a termite colony depends on several factors such as location, food availability and environmental conditions, particularly moisture and temperature. While some colonies remain small, others may contain up to several thousand individuals.
Subterranean termites feed on wood and other material containing cellulose, such as paper, cotton, burlap or other plant products. They cannot digest cellulose directly, so they depend on large numbers of one-celled animals (protists) to break down the cellulose to simple acetic acid, which termites can digest.
Damage Caused by Subterranean Termites
Initially, subterranean termites feed on dead trees and brush, but when land is cleared of this material they attack the structures of houses built on these sites. Termites can enter buildings through wood in direct contact with the soil, wither by building shelter tubes over or through foundations, or by entering directly through cracks or joints in and under foundations, causing significant damage to structures.
Subterranean Termite Control – Signs of Infestation
Swarmers, wings or damaged wood, are clear signs of infestation. Generally, the first signs of infestation homeowners notice is the presence of swarming reproductives on window sills or near indoor light. Nearly always, swarmers inside the house indicate an active infestation in the structure. Outdoor swarmers is a natural phenomenon, but should warn that termites are near. The presence of wings, discarded by swarmers as a natural part of their behavior, is another indication of termite infestation. They can be generally found near emergence sites, on window sills or in cobwebs. In addition, shelter tubes going up the sides of piers, utility entrances or foundation walls are also signs of infestation.
Wood damage is rarely found initially, but it is a definite indication of termite problems. Any wood-to-soil contact is a potential site of entry into a home, and any wood that yields a dull, thudding sound when struck should be examined. Probing suspected areas with a sharp, pointed instrument such as a screwdriver or an icepick will disclose termite galleries or damage.
Subterranean termite control measures include reducing the potential for infestation, preventing termite entry and applying residual chemicals as remedial subterranean termites treatment methods.
Thorough termite inspections can determine whether infestations and damage are present, whether remedial control measures are necessary and what conditions can encourage subterranean termite infestation. Inspections can be performed by anyone with knowledge of the basic construction elements, the environmental requirements for termite survival and the behavior of subterranean termites.
Subterranean Termites Inspection – Necessary Tools and Equipment
Necessary tools and equipment to perform a termite inspection include a flashlight, an ice-pick or sharp-pointed screwdriver, ladder and protective clothing (coverall, bump cap, rubber knee pads), as well as a clipboard, graph paper and a floor plan or sketch to record inspection findings accurately and ensure that the entire structure has been examined. A moisture meter can detect increased moisture levels in the shelter tubes hidden behind walls, and high moisture conditions that encourage subterranean termite infestation.
Outdoor Termite Inspection – What To Look For
Examine the foundation of the house, garage and other structures, looking for shelter tubes coming from the soil. Pay particular attention to connecting patios, attached porches, areas near kitchens or bathrooms and narrowly confined or places that are hard to see. Examine the soil moisture around or under the foundation to determine if faulty grade construction creates moist areas next to the structure and also inspect behind closely planted, dense shrubbery or foliage. Check window and door frames and where utilities enter the structure, observe roof eaves and guttering and check for defects that might cause leakage and eventual wood rot. Note any earth-to-wood contact such as fences, trellises or stair carriages. In addition, open and check any exterior electrical meter or fuse boxes set into the walls, as it is a common point of infestation. Inspect any wood materials near swimming pools, as they may be splashed frequently and remain moist.
Indoor Termite Inspection
Check exterior porches, doors and window facings, baseboards and hardwood flooring, but be careful not to deface finished wood when probing. Inspect any attached earth-filled porches and examine all joints, cracks or expansion joints in the foundation, as well as any unusual blistering in paint or wallboard surfaces. Discoloration or staining on walls or ceilings may be an indication of eater leaks that can decay wood and favor termite infestation. Pay special attention to where plumbing or utility pipes enter the foundation or flooring. Check the floor covering for split or raised areas and carefully inspect the plumbing, particularly in bathrooms on slab construction. There should be access to the bath trap area, but if there is no access build a removable plumbing hatch for periodic inspection.
Next, check the attic for shelter tubes, water leakage, damaged wood or wood rot. If the house is of pier and beam construction, check the area between the floor and the underlying soil (crawl space), and examine the inside of the beams, chimney bases, hearths or piers for shelter tubes. Inspect areas underneath or close to earth-filled porches, patios, planters and bathrooms for water leakage and termite damage. Check the top of the foundation wall where the floor and the wall intersect, and examine plumbing and utility lines passing through the floor of foundation walls.
Chemical Management of Subterranean Termites Infestation
Chemicals applied to the soil can deter attacks for many years, so in order to prevent termite infestation develop a barrier of chemically treated soil between the structure and deeper soil areas. Liquid termicites should be applied to the soil inside and outside foundation walls, around piers and other supports and around utility entrances. In cases such as foundations of concrete blocks or bricks the insecticide must be pressure-injected through drill holes into foundation walls. For slab foundations, extensive drilling and pressure injection are often necessary in the foundation as well as under earth-filled porches, around fireplaces and along adjacent patios and sidewalks. Proper subterranean termite treatment methods will kill subterranean termites and avoid damage to structures, but annual inspections should be performed.