Phylum Arthropoda
Subphylum Hexapoda
Class Insecta
Order Isoptera
Common names: termites, white ants
Overview
Isoptera, or termites, are a small order of social (eusocial) insects closely related to cockroaches. They are best-known for their eusocial colonies in which individuals of both sexes live together in large family groups and labour is divided among individuals that are morphological and behaviourally specialised (castes) as reproductives, and sterile soldiers and workers. Termites have relatively short antennae, mandibulate (chewing) mouthparts and two pairs of membranous wings of equal length. Wings are present in reproductive castes only and are shed after mating. The soldiers have greatly developed and modified heads that either contain large muscles to operate the pincer-like mandibles (mandibulate soldiers) or glandular tissue that sequesters a noxious fluid through a tube on the front of the head (nasute soldiers) Both workers and soldiers have reduced or no eyes. Termites are small to medium-sized insects ranging from 3�20 mm in length with a pale, elongate body, which, along with their social behaviour, gives them their other common name, �white ants�. Termites are cryptic insects that typically inhabit dark nests and tunnels and are rarely seen. However, their presence is often obvious because of the large, distinctive mounds they construct or the damage they cause to man-made wooden structures.
Distribution and diversity
Termites are found throughout Australia, although they are considerably less speciose in tropical rainforests of the continent. Around 2,600 are described worldwide with 263 species described from 40 genera in five families from Australia. It is thought that many more remain to be described and a total number of around 450 species has been estimated.
Life cycle
Termite colonies produce a reproductive caste when they have reached a certain size. The male and female termites fly away from the nest to mate and begin new colonies, typically on warm, humid nights. They shed their wings and females attract a male. Sperm transfer is direct. After mating, individual pairs build a new shelter in which the female lays a small clutch of eggs that will develop into the first workers of the new colony. When this first brood is able to begin foraging, enlarging the new nest and feeding, the queen will lay eggs almost continually, rapidly increasing numbers in the colony which may ultimately consist of over a million individuals. The nymphal termites resemble adults and may moult up to 10 times before maturity. The king and queen termites can live for many years.
Feeding
Termites feed on a wide variety of plant material, including wood, bark, leaves, litter, grasses, fungi and herbivore dung. Some species forage on the surface at night, collecting grasses which they take back to be stored in the nest. Others avoid light altogether and build tunnels to travel between the nest and their food source. To digest the plant cellulose, termites have symbiotic bacteria or protozoans in their gut. Individual species are very selective feeders and may be grouped according to their feeding behaviour. The commonly used groupings are: subterranean, soil-feeding, dry wood, damp wood and grass-eating. Of these, subterranean and dry-wood termites are primarily responsible for damage to human structures.
Ecology
Termites are usually detected by their prominent earthen mounds (called termitaria), which may be as high as 3�4 m in some areas depending on the species. Some termites build smaller earthen nests in tree stumps, in hollow or living trees; others construct a complex network of subterranean tunnels connecting larger galleries. Those species that feed on wood do not build nests but live within the galleries they excavate in the wood. In Australia around 20 species of termites cause economic damage to living trees, crops, pastures, orchards, stored timber and wooden man-made structures. Of these, two genera, Coptotermes and Mastotermes, are the most significant. Termites however, are also of considerable ecological importance in recycling dead plant material, this contributing to soil formation, turnover, water penetration, aeration and nutrient cycling.
Termite colony in Two People's Bay, Western Australia
Image credit: Photographer: Mark Harvey
� Western Australian Museum
Termites and alates (winged termites). Jarrahdale, Western Australia.
Image credit: Photographer: E.S. Volschenk � Western Australian Museum
Termite mound in Carnarvon National Park, Queensland.
Image credit: � John Jennings
Termite mound near Mt Magnet, Western Australia
Image credit: Photographer: Mark Harvey � Western Australian Museum
