Australian meat ants

Page last updated: Monday, 4 April 2022 - 10:18am

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Australian meat ants (Iridomyrmex purpureus gp) are a native ant species. They are also known as the 'gravel' ant or 'southern' meat ant and are commonly encountered in the southwest region of Western Australia. The genus Iridomyrmex is widespread across Australia. Meat ants do not sting but are known for biting aggressively when interfered with.

 

Description

The adult meat ant is large, reaching around 10-12 mm in length. They have reddish-brown fore parts and a dark abdomen. Other colour forms have been reported: orange, reddish-purple or blue with a dark abdomen. Their body is covered with sparse short hairs (visible under a microscope).

Biology and habits

Meat ants build large nests, creating raised mounds of dirt commonly up to 1.5 m in diameter. The mounds have many entrances leading to separate galleries and nesting chambers. The Australian Museum reported there are super nests (interconnected nests) that stretch up to 650 meters. The mounds are usually covered with gravel or sticks, which act as a heat sink, trapping solar energy during the day. Mounds are usually located in open, unshaded areas and will relocate nests that become shaded by overhanging branches.

Meat ants travel in long trails that radiate from the mound. The trails are very obvious as they are cleared of vegetation. Also, some ants scatter throughout the territory in search for food. They forage during the day in temperatures ranging from about 15 to 43 degrees Centigrade. They are mainly active in the warmer months from spring to late autumn.

They are omnivorous; their food includes other insects, some seeds and honeydew (a sugar-rich liquid exudate of aphids and some scale insects). Meat ants 'farm' aphids and scale for the honeydew and cause outbreaks of the pests in trees and in orchards. Black sooty mould often accompanies the outbreak of these sap-sucking insects as airborne mould spores settle and grow in the honeydew.

Social life and colonies

Meat ants usually build their colonies in open areas such as paddocks and dirt tracks. Many colonies may be found in one area, but ants from different colonies will fight each other. When a colony's territory is invaded (by other insects, animals or people), large numbers of meat ants rush out of the nest to defend themselves and their territory. Large numbers also emerge to exploit a new food source when one is located.

During spring, new queens leave the colony and start to dig a new nest in the vicinity of the old one. Often, workers from the mature colony kill queens that dig too close to the existing nest, but sometimes they help them start the new colony. Many new queens are also killed by predators such as birds and other insects.

Reputation as pests

Meat ants are very territorial in their behaviour and aggressive toward intruders. They can be a nuisance because of their foraging activity in and around homes. They often nest near farm gates, which can be very unpleasant for the person opening the gate as the ants crawl up their legs and bite. Orchardists and wildflower growers are sometimes bitten by meat ants when picking their produce.

Cattle and sheep are often irritated by the ants climbing up their legs and snouts and biting them. Large numbers of meat ants are often found in places such as milking sheds and near feeding troughs.

Control treatment for meat ants

If the ants are confidently identified as meat ants, insecticide sprays registered for ant control can be used to treat meat ant mounds and greatly reduce or eliminate meat ant numbers. Registered chemicals include bifenthrin, permethrin and chlorpyrifos. Follow the mixing instructions on the pack and spray the mounds, including approximately 100 mL down every hole. These spray products can be purchased from garden centres, hardware stores and agricultural chemical retailers.

Specimen identification

After reading the above information, if there is still uncertainty of the type of ant, a specimen may be sent in to Pest and Disease Information Service (PaDIS) at the Department of Primary Industries and Regional Development. Simply mail to:

Department of Primary Industries and Regional Development
Pest and Disease Information Service
3 Baron Hay Court
South Perth WA 6151
(or Locked Bag 4, Bentley Delivery Centre WA 6983)

Contact information:
Pest and Disease Information Service (PaDIS)
Phone: (08) 9368 3080
Email: padis@dpird.wa.gov.au

When sending a specimen for identification note the following information:

DO NOT SEND LIVE ANTS IN THE POST

  • ants can be collected using the sticky side of transparent sticky tape and gently adhereing this to white paper or folding back onto itself. Alternatively brush ants into a container and seal. Place the ant sample in the freezer for 1 hour or longer. If taking multiple samples, label with the collection location.
  • include your name (the collector), a contact telephone number, email address and postal address.
  • physical location and where you saw it, i.e. street address (GPS location is ideal) and where on the property you noticed the ant.
  • description of the type of damage caused or other reason for submitting the sample.

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080