Introduction about Subterranean Termites

Most pest species of subterranean termites in North America belong to the endemic genus Reticulitermes. Reticulitermes species are found in every state in the continental United States except Alaska, but are most common in the warm and humid southeastern region. The eastern subterranean termite, Reticulitermes flavipes (Kollar) is the most widely distributed and is found in the entire eastern region of North America as far north as Ontario, Canada, and south to Key Largo, Florida. Because of their cryptic nature, structural infestations of subterranean termites are usually not visible. Most people become aware of an infestation when annual flights of winged termites (called alates) occur in structures. As with other termite species, Reticulitermes colonies contain three primary castes; the reproductives (king, queen, alates, alate nymphs, and supplementary reproductives), soldiers, and workers. Alates and soldiers are used for species identification.

Damage

Because subterranean termites consume cellulose, the main structural components of plant cells, any wood material in a house is a potential food source, but they may also damage non-wood material in search of food. Termites rarely show themselves in the open, and infestations can be difficult to detect until damage becomes severe. The surface of severely damaged wood may appear blistered or peeling, as termites hollow out the wood leaving a paper-thin surface. Eastern Subterranean Termites tend to cover the wood they feed upon with soil, thus giving wood a more “dirty” appearance. However, it is not advisable to identify the termite species based solely on damage as there are many exceptions.

Prevention of Subterranean Termites

Because subterranean termites forage in soil, it is important to keep structural lumber from direct contact with soil. Hence keeping the lower foundation walls and siding clear of vegetation or mulch makes it easier to inspect for termite shelter tubes. Subterranean termites need moisture for survival. Hence leaky plumbing, air conditioning condensate, and any portion of a building and its perimeter that collects excessive amounts of moisture should be corrected to maintain an environment less attractive to subterranean termites.

Preventative Bait Stations

With baits, small amounts of product are deployed like edible ‘smart missiles’ to knock out populations of termites foraging in and around the home. Therefor termites consume the bait and share it with their nest mates, resulting in a gradual decline in termite numbers. However a comprehensive baiting program then seeks to maintain a termite-free condition on the customer’s property through ongoing inspection, monitoring and re-baiting as needed.

Control

Soil Treatments

Spraying the soil beneath the foundation with liquid insecticides has been the traditional method for subterranean termite control. Basically the objective is to place a chemical barrier between termites and the structure to be protected. Before the foundation is poured, soil termiticides are applied onto sub-slab soil to form a horizontal barrier. A vertical barrier is applied around the perimeter after the foundation is poured. This pre-construction treatment is mandatory in many of the United States. Also post-construction treatment consists of drilling holes through slabs and injecting insecticides under the foundation and by drenching trenches dug along building foundations.

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Reference

• Grace J K, Su N-Y. 2001. Evidence supporting the use of termite baiting systems for long-term structural protection. Sociobiology 37: 301-310.
• Lenz M, Runko S. 1994. Protection of buildings, other structures and materials in ground contact from attack by subterranean termites (Isoptera) with a physical barrier – a fine mesh of high-grade stainless steel. Sociobiology 24: 1-16.
• Rust M, Su N-Y. 2012. Managing social insects of urban importance. Annual Review of Entomology 57: 355-75. (doi: 10.1146/annurev-ento-120710-100634)
• Scheffrahn RH, Mangold JR, Su N-Y. 1988. A survey of structure-infesting termites of peninsular Florida. Florida Entomologist 71: 615-630.
• Su N-Y, Scheffrahn RH. 1992. Penetration of sized-particle barriers by field populations of subterranean termites (Isoptera: Rhinotermitidae). Journal of Economic Entomology 85: 2275-2278.
• Su N-Y. 2019. Developement of baits for management of subterranean termites. Annual Review of Entomology 64: 115-130. https://doi.org/10.1146/annurev-ento-011118112429.
• Su N-Y, Ban PM, Scheffrahn, RH. 1993. Foraging populations and territories of the eastern subterranean termite (Isoptera: Rhinotermitidae) in southeastern Florida. Environmental Entomology 22: 1113-1117.