Termites - Isoptera
Termites – Isoptera
Termites are highly specialised social (eusocial) insects. They form colonies or nests and have three distinct forms of castes. The reproductive caste includes the parent king and queen, supplementary queens ? known as neotenics, and immature reproductives which develop wings (alates). The worker caste, which is the food gatherer and builder, is sterile, wingless and lacks pigmentation in most species. The soldier caste has an enlarged pigmented head which often includes a pair of massive jaws used for defence of the colony.
There are a wide diversity of mature colony population sizes ranging from several million down to about 50 individuals, depending on the termite species. The colony may be a large and obvious mound, or it may be completely hidden inside a tree or underground. All of the large colony builders are subterranean in that they can travel underground to a source of food some distance away. Another group known as dampwood or drywood termites, make their small colonies inside dead branches on trees and do not move beyond their host tree. In Australia all of the pest species are of the subterranean type.
Termites have a gradual life cycle which, unlike true ants, lacks the pupal stage. The mature reproductives have two pairs of almost equal sized wings in ants the hind wings are always much smaller than the fore wings. At the right moment, usually during a thundery evening in late spring or early summer when the humidity is very high, the alates fly out from the parent colony. The right conditions can trigger a massive alate release from many same species colonies over a wide area. Each one of these alates is a potential king or queen of a new colony but fortunately very few survive long enough to do so.
Termite Species44-Termite-E-Subterranean-Termite-
Termites belong to the Order Isoptera. This Order is one of the smallest, containing less than 2,500 species worldwide. In Australia there are an estimated 350 termite species in five Families.
The Atlas of Australian Termites has a list of 267 named Australian species with maps showing the known distribution of each one.
The identification of termite Families makes use of the antennae, tarsi (feet), cerci (rear end feelers), pronotum (top of thorax just behind head), fontanelle (a pore on the top or front of a soldiers head), and in alates, the wings. The differences are combined to form a key to identification. The following example is a key to Australian termite families based on the soldier caste and taken from Insects of Australia.
SOLDIERS
1. Tarsi 5-segmented Mastotermitidae
Tarsi 4-segmented (rarely with a rudimentary 5th segment. 2
2(1) Cerci long, 4 or 5 segmented Termopsidae
Cerci short 2-segmented 3
3(2) Pronotum with well developed, elevated, convex anterior lobe and as a result,
saddle-shaped Termitidae
Pronotum transversely arched to almost flat, without elevated anterior lobe,
concave to slightly convex in front 4
4(3) Fontanelle present Rhinotermitidae
Fontanelle absent Kalotermitidae
There is a separate key for alates. Pictorial keys used in Termites and Other Common
Timber Pests illustrate the different body parts and can be easier to follow if unfamiliar with the descriptions alone.
Once the Family has been determined the head of the soldier is used to identify the Genus of a specimen termite. The head shape and size plus the jaws, show sufficient differences to give a reliable identification.
Species identification is more difficult but knowledge of colony form and the size of the specimens, can be used to identify many of the more common species.
Termites As Pests
Most termite species are not pests of buildings. Many feed only on plant stems, ground surface debris or organic material in the soil. In the Sydney region there are just four species which can be classed as serious pests in buildings.
Coptotermes acinaciformis is estimated to cause up to 80% of building damage in Australia. C. frenchi, Schedorhinotermes and Nasutitermes exitiosus are other serious pests. There are perhaps another four or five species which sometimes enter buildings but seldom cause much damage to them. Above the Tropic of Capricorn Mastotermes darwiniensis, the giant northern termite (one of the few termite species with a specific common name), is probably one of the most damaging termites in the World. It is fortunate that this termite inhabits the parts of Australia with the lowest human population.
Termites have their natural place in Australia, the few species that cause problems to us should not condemn the majority which form a vital part of the land with their nutrient recycling and food-chain contribution.
The following list of books provide further information about termites and include the three books cited in this paper.
Atlas of Australian Termites. By J.A.L. Watson and Hilda M. Abbey. Published by CSIRO.
Building Out Termites. By Robert Verkerk. Published by Pluto Press.
Insects of Australia Vol. 1, pp. 330-347. By CSIRO. Published by Melbourne University Press.
Termites and Other Common Timber Pests. By Phillip Hadlington. Published by New South Wales University Press.
Termites of the Canberra Region. By J.A.L. Watso. Published by CSIRO.
Termites of the Top End. By Alan Anderson and Peter Jacklyn. Published by CSIRO.
Urban Pest Control in Australia, By Philip Hadlington. Published by New South Wales University Press.