Common names: African harvester termite (Eng.); grasdraertermiet (Afr.); moloto (Sepedi); Imvungu (isiZulu); iphondondo (Tshivenda).

Harvester termites are social insects belonging to the order Blattodea, which are found throughout sub-Saharan Africa, especially in the savanna and semi-arid regions. They can easily be recognised when they out are in large numbers collecting grass.

Description/How to recognize a…

Harvester termites’ body size ranges differ according to caste; with soldiers being 15 mm, workers 8–13 mm, and the queen 25 mm in length. They are identified by their long bodies with segmented design and pale brown to brown colouring. Workers have dark brown heads and bodies with brown and cream stripes. Jaws of soldiers are robust, toothed and strongly curved inwards. The cerci, which are a pair of appendages on the back of the termite, have three to eight segments.

Life cycle

The first nymphs (sexually immature offspring) emerges about three weeks after the queen started laying eggs. At first, the nymphs are defenceless, as they still have soft mandibles and are unable to chew food on their own. The workers feed the young, bringing up food that has been stored in their guts. The nymphs grow in size and their exoskeletons hardens fast. They shed their skin, or moult, when this covering cracks open. A new exoskeleton is already present underneath each nymph. The nymphs have to wait for this new covering to harden because it is first soft. They then resume eating and growing. The nymphs’ mandibles become hard after a second moult. They are prepared to serve as the colony’s first workers.

Getting around

Harvester termites mostly move around on three pairs of legs. Flight, with four deciduous wings, only happens as a result of seasonal, local atmospheric and other factors. The flight is a dispersal flight, not a mating flight. The temporarily winged termites are called alates. Usually, the alates fly poorly, alight after a short flight and lose their wings by twisting and turning their bodies.

Communicating

Harvester termites communicate in a variety of ways, through chemical, acoustical, and tactile signals. They leave a chemical scent, i.e., a pheromone trail, which indicates the direction of food. These signals are released by a sternal gland on the termite’s belly, and they make noise through rhythmic movements, shaking and slamming their heads against the ground, a behaviour that is more common in soldiers. They also communicate by vibrating the galleries to warn other termites of potential danger.

Distribution

Harvester termites are found in tropical and subtropical regions worldwide. In South Africa, they can be found in eight of the nine provinces, excluding the Western Cape, in a variety of habitats, and three biomes, namely the Grassland, Nama Karoo and Savanna biomes.

Habitat

Harvester termites are usually found in grassland and savanna environments. They are adaptable to mostly arid and semi-arid environments, preferring regions with average to light rainfall. They prefer damaged and overgrazed areas. They are distributed throughout the countries of southern Africa, including South Africa, Botswana, Zimbabwe, Namibia  and Lesotho. The termite colony resides underground in nests that can be found both close to and far below the soil’s surface. The tunnels built by the workers link these nests together.

Food

The primary food for harvester termites is grass, however they also feed on a variety of other plant and fungal material, including dead wood, fungal bodies and herbaceous plants. They primarily graze in bright sunlight, particularly in autumn and early winter. They feed on cellulose, either directly from dead or living plants or indirectly through fungi that develop on decaying plant material within nests.

Harvester termites exhibit a foraging behaviour where they harvest grass and other plant materials, which serves as a source of food, from their surroundings. Most workers avoid foraging in open and unprotected areas; they form linear congregations and make runways and sheeting to escape predation. Workers recruit extra fellows in the presence of plenty food supplies through the release of a phagostimulant (feeding-stimulating) pheromone, a hormone used to attract other workers. Semiochemical pheromone is a hormone that harvester termite workers use to communicate with other workers, whilst workers outside emit a trail of pheromones to guide members between food and other colonies. Workers return to the colony after collecting food and feeding other members, including the soldiers and queen.

Termites pass waste shortly after eating, and because the waste was passed fast, it still contains nutrients from the food. Workers and soldiers eat these nutrients. Then, when other members continued to ingest their faeces, these workers rapidly pass their own waste. As a result, the food is shared by the entire colony, which contributes to the colony’s survival.

SEX and LIFE CYCLES

Sex

A termite colony is made up of functional reproductives (a king and queen), workers, soldiers and immature individuals classified as larvae (without wings) and nymphs (with wing pads). There are two types of reproductive functions: primary and supplementary. The king and queen are the primary reproductives; they have harder and darker bodies and develop from winged adults. Their role in the colony is to produce offspring, where the queen lay thousands of eggs in a day and the king is her consort, and he mates with her regularly. Even though some workers die away, the queen will continue to produce eggs for years, and the colony will expand. The queen regulates the population of the colony. When there are many workers, some of the nymphs receives a hormone that allows them to grow into alates that can later disperse and become functional reproductives when they start their own colony.

The supplementary reproductives are the workers who have been promoted to higher castes; they are provided with a special diet that contains nutrients to assist them with reproduction, and they are either noticeably darker with short wing pads or very dark without wing pads. They assist in reproduction when the colony grows bigger or when the primary reproductive pair dies, there can be hundreds of secondary reproductives to replace the primary pair. The reproductives also contribute to species dispersal by colonising, selecting new colonies, feeding by harvesting grass and other plant materials for food, and caring for the colony’s first offspring.

Family life

The non-breeding individuals in a colony are the workers and soldiers. The sterile individuals, the worker and soldiers, are wingless and some are blind. The sterile caste sometimes occurs in different forms (polymorphism). While some of the workers transport the eggs to the nursery rooms, others feed and clean the king and queen. Some workers work on the nest, adding new tunnels and rooms, while others feed the hatchlings. Workers also expand the queen’s chamber since the more eggs she produces, the longer and larger she grows to be.

Some nymphs develop into soldiers, which have large heads and jaws for fighting off enemies like ants. Soldiers accompany workers to watch over and protect them. The colony has two different classes of soldiers: major soldiers and nasute soldiers. Major soldiers typically guard the queen and nursery while remaining within the nest. They may group their heads together in a tunnel so that enemies cannot pass through because they have huge heads. Nasute troops often accompany and guard workers when they forage. Their large, pointed snouts are filled with a sticky, toxic fluid that is sprayed at their enemies. The substance can be harmful as they cause a burning or irritating sensation and can also be deadly to small opponents.

THE BIG PICTURE

Friends and Foes

A variety of invertebrates (e.g., beetles and flies) have evolved to live in termite nests. They have gotten so adapted to living in close association with termites through the course of evolution that they cannot survive on their own and have developed structural and physiological adaptations. These species are known as termitophiles. Animals such as other termites and ants compete with harvester termites for food.

Mammals such as the ground squirrel and aardwolf, reptiles and bird species feed on harvester termites. The interaction is mutualistic in that the predators acquire food from the termites and the harvester termites benefit from having their numbers controlled.

Smart Strategies

Harvester termite nests are comprised of a mixture of soil and saliva. In a similar way to an insect’s shell, the nest wall acts as a barrier to predators. The inside environment of the nest is kept at a constant temperature and humidity level, is independent of the external environment, and the galleries allow for sufficient air circulation within the colony. When harvester termites nest get damaged, it is repaired as soon as possible by workers, as the colony will be vulnerable to predation until it is repaired.

Poorer world without me

Termites are called ‘ecosystem engineers’ as they form part of and influence the majority of the world’s ecosystems. They feed on grass, wood and other plant materials, assisting in the processes of nutrient cycling and soil formation. The harvester termite nests increase soil variability through changing soil characteristics, thus enhancing plant development. However, when they cause harm to crops, gardens, or grasslands during their foraging activities, they turn into pests.

People & I

Harvester termites are harvested by the Khoisan people during their swarming times. If swarms gather near the camp, the women will follow the flying termites to their underground nests, which are normally hidden. The holes are made wider using digging sticks, then filled with grass to keep adult termites out, and the nymphs and larvae are collected. If just a few termites are collected, they will be eaten raw after the heads and wings have been removed. If a large number of termites are collected, they are brought home and cooked in hot ash and sand. Soldiers and workers are not gathered because they are less desirable due to their unpleasant and bitter taste.

Conservation status and what the future holds

Harvester termites are categorised as being of the Least Concern due to their abundance.

RELATIVES

Termites are members of the Superorder: Dictyoptera, which includes cockroaches and mantids. Within that order, they are related to cockroaches, and their sister group is the wood roach. Harvester termites, like cockroaches, lay their eggs in an oothecal-like mass and have a transversely folding hind wing. Workers resemble southern harvester termites (Microhodotermes viator), although this type has a more evenly brown abdomen with unclear striping.

Official Common Name: African Harvester termite
Scientific Name and Classification:
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Blattodea
Family: Hodotermitidae
Genus: Hodotermes
Species: H. mossambicus Hagen, 1853

References and further reading

  • Andrews, S. & McClintock, D. 1982. Notes on Restio subverticellatus. The Plantsman 37: 230–233.
  • Bignell, D.E. & Roisin, Y. 2011. Biology of termites: A modern synthesis. Springer, New York.
  • Brown, N., Jamieson, H. & Botha, P. 1998. Grow restios. Kirstenbosch Gardening Series. National Botanical Institute, Cape Town.
  • Eggleton, P. 2011. Termites: an overview. In: D. Bignell et al., Biology of termites: a modern synthesis, pp. 1–24. Springer, New York.
  • Khan, M., A. & Ahmad, W. 2018. Termites and sustainable management. Springer, New York.
  • Krishan, K. & Weesner, F.M. 1969. Biology of termites. Academic Press, New York.
  • Lesnik, J.J. 2014. Termites in homini diet: a meta-analysis of termite genera, species and castes as a dietary supplement for South African robust autralopithecines. Journal of Human Evolution.
  • Lewis, V. R. 2003. Isoptera (Termites). In: V.H. Resh & R.T. Carde,. Encyclopedia of Insects, pp. 604–607. Academic Press, California.
  • Markle, S. 2008. Termites: hardworking insect families. Lerner, Minneapolis.
  • Picker, M. Griffiths, C,L. & Weaving, A. 2004. Field guide to insects of South Africa. Struik, Cape Town.
  • Stenkenwitz, U. & Kamler, J.F. 2008. Birds feeding in association with bat-ear foxes on Benfontein Game Farm, South Africa. OstrichJournal of African Ornithology 79(2): 235–237.

Author:
Popo Mosehle

Scroll to top