The colonies of C. formosanus contain three primary castes: the reproductives, soldiers, and workers. The majority of the nestmates are workers that are responsible for the acquisition of nutrients, i.e. cellulose in the wood. The head width of the white soft-bodied worker is approximately 1.2-1.3 mm and the body length is approximately 4-5 mm. The thorax is narrower than head width. The alates and soldiers are most useful for identification. The alates are yellowish-brown and 12-15 mm long. There are numerous small hairs on the wings of these comparatively large swarmers. The alates are attracted to lights, so they are usually found near windows, light fixtures, windowsills and spider webs, around well-lit areas. The soldiers are approximately the same size as the workers and have an orange-brown oval-shaped head, curved mandibles and a whitish body. When disturbed, the soldiers readily attack any approaching objects and may secrete a white gluey defensive secretion from the frontal gland. There are more soldiers (10-15%) in a C. formosanus colony than in a subterranean termite colony, such as Reticulitermes spp. (1-2%).
Occasionally the foraging tubes may be observed on the wood surface or tree trunk. During the swarming season (April to June), elongated mud tubes that serve as flight exit slits may be seen. The damage by C. formosanus tends to occur in places with high moisture including the bathroom, kitchen sinks and leaky roofs. An acoustic emission device (AED) may be used to locate sites with feeding activity, but most AEDs have a limited detection range (Scheffrahn et al., 1993).
Related invasive species
- Coptotermes formosanus
Related Farm Practice
- Pests
- Light
- Damage
- Materials
- Soil
- Heartwood
- Identification
- Wood
C. formosanus is often transported by boats and shipping containers to port cities before being carried further inland via landscape materials such as railroad ties (railway sleepers). This may explain the current C. formosanus distribution in the USA with coastal areas more densely infested than inland areas (Hochmair and Scheffrahn, 2010). Temperature and humidity are primary factors affecting the establishment of C. formosanus, and it is potentially invasive to areas of high humidity approximately 35° north and south of the equator (Su and Tamashiro, 1987). Competition from native species is another limiting factor for many exotic pests, but C. formosanus is more aggressive and is known to out-compete the endemic termites such as Reticulitermes species. Another factor that has allowed the successful establishment and spread of C. formosanus in exotic areas has been the pest control industry's heavy reliance on soil termiticide barriers for subterranean termite control since the 1950s. Numerous studies, using mark-recapture methods, have revealed that a single colony of C. formosanus might contain several million termites that forage up to 100 m in the soil (Lai, 1977;Su and Scheffrahn, 1988). These agree with the results of excavation studies for C. formosanus colonies (Ehrhorn, 1934;King and Spink, 1969). Because of the large colony size, the application of soil termiticides beneath a structure does not usually have a major impact on the overall population, and the surviving colony continues to produce alates that can further infest nearby areas. Once established, C. formosanus has never been completely eradicated from an area. The dependency of soil termiticide barriers as the primary tool for subterranean termite control is probably the main reason for the establishment and spread of C. formosanus from four isolated port cities in the 1960s in the USA to all south-eastern states by 2001.
Large colonies of C. formosanus generally live underground. When these termites invade a house aboveground, the foraging tubes of approximately 0.5-1 cm in diameter may be found connecting the soil and the infested house. In severe infestations, C. formosanus hollows out the wood leaving a paper-thin surface and the hollowed wood surface may look blistered or peeled. Another characteristic of C. formosanus is carton nest material that is made from termite faeces, chewed wood and soil. The honeycomb-like carton nests can be as large as 1-1.5 m in diameter and are usually found in structure-voids such as between walls and beneath sinks.
C. formosanus is an opportunistic feeder of any material containing cellulose. A large number of living plants are known to be attacked by C. formosanus, but it usually does not kill the plants unless the root system is significantly damaged (Lai et al., 1983;La Fage, 1987). Records show that living citrus, eucalyptus and sugar canes (Saccharum sp.) may be killed by C. formosanus, but in most cases damage occurs in the heartwood of a tree. The infested trees may be more easily blown over by high winds due to the loss of structural strength. The pest status of C. formosanus is most significant when it attacks wood products in a house such as structural lumbers, cabinets, etc. C. formosanus is also known to damage non-cellulose materials in search of food, including plastic, concrete and soft metal. Occasionally underground high-voltage power lines may be penetrated by C. formosanus, resulting in an area-wide power cut.