Of the estimated 4-5,000 species present in Australia very few are troublesome, and these are mostly “vagrant” or “tramp” species which have been accidentally introduced from overseas. The tramp species (the Singapore Ant, the Coastal Brown Ant, the Argentine Ant, the White-footed House Ant, Pharaoh’s Ant, and the Black House Ant) infest buildings in search of water and food and will take all kinds of domestic foods, ranging from oils and butter to sweet substances, meats and grain-based items like bread and biscuits. Most of them are capable of nesting indoors in wall spaces, ceiling, and wall insulation, crevices in furniture, etc.
Most also tend sap-sucking bugs like aphids and scale insects on plants. The protected bugs produce sweet secretions attractive to the ants and can be vectors of plant bacterial, fungal and viral diseases. When dense populations of ants nest in the ground they can induce damage to soil structure, causing crops to fall over, and they can undermine the foundations of paths and small buildings.
Several species are attracted to plastics and cause damage to irrigation and electrical installations. Several house fires in northern Australia are believed to have been caused by short-circuiting resulting from ant damage. Some ‘”tramp” species have painful stings, while others bite and then spread or spray venom from the tip of the abdomen, so as to irritate the bite wounds.
Several native ant species are also injurious to human enterprise. Most prominent are the Australian Bulldog and Jumper Ants. There are many known cases of severe human allergic reactions (even death) due to their stings. Other troublesome native ants include some of the Meat Ants and the Green Weaver Ants.
All ants live in colonies which typically include a large force of workers and a single, or several queens, along with successive life-history stages, eggs, larvae, and pupae; the composition may vary seasonally. The life cycle of the Red Bulldog Ant, Myrrnecia gulosa, is illustrated further down the page as an example.
All Bulldog Ant species are physically similar and easily recognized by their characteristic head and jaw structure. They differ greatly between species in color and size, ranging from 8mm to 35mm long. They frequent all major habitats from rain forest to desert, coastal to alpine, including urban gardens and parks, but are generally absent from northwestern Australia. They are aggressive insects with potent, painful hypodermic stings. Many people react strongly to the injected venom, sometimes with anaphylaxis, or death (more frequently reported in fact than shark attacks!). Those experiencing bad sting reactions should consult a specialist allergist.
1.) Worker Ants resting on the wall of a nest chamber
|The worker ants of most domestic pests forage in columns and may co-operate in the return of larger items of booty. Adult ants imbibe liquid food, including sweet solutions, meat juices, and the blood of prey insects to maintain their day-to-day energy requirements.|
2.) Winged Male Ant
|Male ants are winged and wasp-like and do not closely resemble the workers or queen. Their function is entirely for reproduction. They do no work in the nests but are released for mating flights, then disperse and die.|
3.) A Queen Ant showing traces of wing stubs on the thorax.
|Queens in most species are much larger than the workers with a more complex thoracic structure. After the nuptial flight, the young mated queens shed their wings and seek a sheltered spot to begin egg-laying. Pest species often have several queens in each nest.|
4.) Eggs being tended by workers in the nest.
|All fertilized eggs are laid by the queen; she is the only mated reproductive in the colony and the mother of all its inhabitants. All ant workers are female, but (with rare exceptions) unable to mate or to lay fertilized eggs.|
5.) Larvae being tended by workers in the nest.
|Larvae feed voraciously as they grow. The brown beetle larva at the lower center was collected outside the nest by a foraging worker and returned as food for the larvae.|
6.) Pupal cocoons and a worker within the nest.
|These yellowy papery sacks are made of silk produced from glands opening near the mouths of the larvae. Inside their cocoons, the larvae change to pupae, and later to adults. All of the other ants featured in this poster have naked pupae, which lack cocoons and can look like white, immobile adults.|
Coastal Brown Ant (subfamily Myrmicinae)
Large-headed major and minor workers of the Coastal Brown Ant, one holding a larva
Originally from Africa, the Coastal Brown Ant, Pheidole megacephala, is prominent in domestic situations in the Perth/Fremantle area; Darwin; and east coast towns, south at least to Sydney. It is considered the major ant pest in many areas. Distinctive large-headed major workers are present along with ordinary workers.
The majors defend the colony and perform special tasks, such as seed-cracking. The waist is 2-jointed, and a string is present. This ant infests houses, stores, and gardens, taking food ranging from sugar to cheese, meat, and bread. Outside it tends sap-sucking bugs and interferes with gardening, cultivation, and harvesting. Tropical crop trees like coffee can fall over because of soil loosening by Coastal Brown Ant nests.
Singapore Ant (subfamily Myrmicinae)
Workers and Soldiers of the Singapore Ant
The Singapore Ant, Monomorium destructor, is common in north-western Australia and is a major nuisance in houses, stores, gardens, and crops. Like the Coastal Brown Ant it has large-headed major workers, a 2-segmented waist and a fairly potent sting. In this species, the extremes between the largest headed majors and the smallest workers (minors) are bridged by a range of ants which grade in size. The most troublesome attribute of this formidable pest is its attraction to plastics in electrical, irrigation and other equipment. The Singapore Ant is a major nuisance in tropical agriculture, especially where hand-cropping is practiced; it tends plant-disease transmitting aphids and other insects and damages soil by its nesting.
Pharaoh’s Ant (subfamily Myrmicinae)
Pharaoh’s Ant Queen with smaller workers, Egg and Larvae
Pharaoh’s Ant, Monomorium pharaonis, is relatively uncommon as a house and store pest in Australia. It has a 2 segmented waist like the Coastal Brown Ant but lacks major workers. It frequently occurs in hospitals, and has earned the alternative name “Hospital Ant”. This species infests foodstuffs of all kinds. Infestations can be quite large, including many queens. The workers may forage over large distances. Pharaoh’s ants commonly nest within the structure of buildings.
White Footed House Ant (subfamily Dolichoderinae)
White-footed House Ant workers feeding on pet food
The White-footed House Ant, Technomyrmex albipes, ranges from SE Asia to Eastern Australia and New Zealand. It is one of the three small, dolichoderine ants which are major pests in Australia. These species lack major workers, they have 1segmented waist nodes and do not sting (their venom is smeared from the tip of the abdomen). All am relatively soft-bodied and easily squashed when crushed between the fingers. White-footed House Ants are dull cloudy black in color, with largely white legs. These ants can live well in gardens and domestic surroundings. They enter houses most frequently in dry periods seeking water in kitchens or bathrooms; and will eat sweet substances or meat. Indoors, nests may utilize any suitable space: wall and ceiling voids, insulation batts, even small, empty, storage containers.
Black House Ant (subfamily Dolichoderinae)
Black House Ants with their Larvae
The Black House Ant, Ochetellus (formerly Iridomyrmex) glaber, occurs in Australia over much of the range of the White-footed House Ant and has similar behavior. It commonly nests within the structure of buildings. O. glaber is adept at importing and tending aphids and other bugs on domestic pot plants. It is a little smaller and stockier than the White-footed House Ant, and more intensely black, with a sometimes subtle, but distinct, purplish blue-green iridescence. The White-footed and Black House Ants have a distinctive strong odor when crushed, but the smell is reportedly imperceptible to some noses.
Argentine Ant (subfamily Dolichoderinae)
Argentine Ant queen surrounded by workers
The Argentine Ant, Linepithema humlie (formerly Iridomyrmex humills), introduced from South America, is a pest in Sydney, Melbourne, Hobart, northern Tasmania, and Perth. Argentine Ant infestations can be immense because the mated queens disperse only a short distance on foot from the nest with a contingent of workers. Colonies thus become continuous and enormous, with hundreds of queens and millions of workers. Even well-secured cupboards and refrigerators are not proof of these efficient marauders. The Argentine Ant is a declared pest but former government control measures have been largely abandoned. L. humlie resembles the White-footed House Ant but it is light brown in color and lacks the strong smell when crushed.
Meat Ant (subfamily Dolichoderinae)
Australian Meat Ant workers tending a sap-sucking bug
One or more native Meat Ants usually occur in dry situations across much of Australia. Iridomyrmex purpureus, is the most widespread. These relatively large dolichoderines do not nest in buildings but have large, roughly circular, low-profile nest mounds, up to several meters in diameter, characteristically surfaced with fine gravel and pebbles, and with many small separate nest entrances scattered on their surfaces. I. purpureus is especially attracted to meat and can be a pest in abattoirs. It can cause structural damage to paths, small buildings, etc. by undermining their foundations.
Green Weaver Ant (subfamily Formicinae)
Green Weaver Ant workers using silk from a larva to weave leaves together
The native Green Weaver Ant, Oecophylla smaragdina, is native across northern tropical Australia. It does not sting, but bites painfully, and sprays venom from the tip of the abdomen, irritating the bite wounds. Oecophylla constructs it (up to) football-sized nests in trees by joining leaves together with silk from the larvae. One colony can include a number of nests on several trees, and enormous populations can develop. It is a major nuisance to people near the nesting trees, especially those harvesting tropical fruit crops like mangoes and citrus. This is considered a serious horticultural and garden nuisance in the Darwin and Cairns areas.