Electric ant

Electric ants, also called little fire ants, are minute and difficult to distinguish from other tiny ants. The purpose of this page is not to identify them definitively, but to rule out enough alternatives that an approach to the authorities is justified. Look for the following characteristics:

• Ants less than 2 millimetres long.
• Ants that are red, orange or light brown, not dark brown or black.
• Ants all about the same size rather than worker castes of different sizes.
• They are slow moving rather than rushing about.
• They form distinct foraging lines.
• They sting, and the irritation can be long-lasting.
• They do not enter and leave obvious ant nests.

Other behavioural clues are given under the heading ‘Behaviour and Location’.

The following features are also helpful, but require a microscope:

• The thorax has two backward pointing spines.
• The thorax is separated from the bulge of the abdomen by a narrow waist consisting of two small segments rather than one.

This ant shows a backward-pointing thorax spine and two small segments before the abdomen bulges. Photo: Pest and Diseases Image Library | Bugwood.org

Workers are 1-1.5 millimetres long.

Look for slow-moving lines of extremely small ants along the edges of concrete paths and walls. Electric ants are not workaholics that build mounds or dig complicated tunnels. They prefer to move into pre-existing spaces providing shade and a little moisture, so they can be found under rocks and timber, in pot plants (including under the bottom and in the saucer), in piles of mulch and garden waste, around the edges of flower beds, and under shrubs. Other places they use include narrow gaps in garden furniture, camping gear and bedding, and behind bark on trees and in forks of branches.

Because electric ants are so tiny, people stung by them can blame mosquitoes or sand flies for welts they develop after enjoying the garden or sitting on the veranda. Gardeners trimming branches or harvesting fruit can attract stings on the neck and torso, from ants falling from foliage. The ants can survive on the water surface, so people in swimming pools are also stung.

On garden plants and fruit trees electric ants (like many other ants) visit aphids, scales and mealybugs to imbibe the honeydew they release, so they can be detected in the company of these.

Pets can indicate their presence. Cats and dogs may be stung by ants attracted to their food and water bowls. Cloudy corneas can indicate electric ant stings to eyes. Stings to the skin can produce a mangy appearance.

If the eyes of pets become cloudy this can be from electric ants stinging their corneas. A mangy appearance can be from electric ant stings to the skin.

Native to Central and South America, electric ants were first detected in Cairns in 2006. They have not found in Australia away from the Cairns region but may occur elsewhere, awaiting detection.

These ants do best in the tropics, but occur as well in some temperate locations, including south-eastern Argentina, Israel, and southern Spain, suggesting a capacity to survive in Australia in southern NSW and southern Western Australia.

Electric ant. Photo: © The State of Queensland | Department of Agriculture and Fisheries

Australia has vast numbers of tiny ant species, few of which sting. Three are illustrated here, either because they are especially widespread and common around homes, or because they sting. All three are introduced.

Big-headed ants (Pheidole megacephala) are tiny and slow-moving, but they come in different sizes rather than all looking the same. The major workers (soldiers) have massive heads. Big-headed ants are often (but not always) darker than electric ants. They do not sting.

Big-headed ants with two major workers on the left. Photo: Sarefo | CC BY-3.0

Argentine ants (Linepithema humile) are larger (2-3 millimetres long), longer-looking, faster, and typically darker. They swarm when disturbed but do not sting.

Argentine ants. Photo: Whitney Cranshaw, Colorado State University | Bugwood.org

Red imported fire ants (Solenopsis invicta) are larger (2-6 millimetres long) and come in multiple sizes. Their abdomens are darker than their head and body. They are aggressive, often stinging en masses when a nest is disturbed. They are another ant of grave concern that should be reported to authorities. See our red imported fire ant insect watch profile.

Red imported fire ants. Photo: Barry Rice | sarracenia.com | Bugwood.org

Electric ants can sting, but they are slow-moving, and a single sting isn’t very painful unless you have an allergic response, in which case a welt can develop and a histamine injection may be needed. A couple of ants can be killed with a knockdown insecticide, or flicked into a jar or zip-lock plastic bag then killed in the freezer compartment of the fridge.

Electric ants are attracted to baits, such as a thin coat of peanut butter smeared on small sticks placed in shady areas around the garden. These can be checked an hour later. If suspicious ants are found, pop the stick with the peanut butter in a zip lock bag into the freezer for 24 hours.

Think you’ve found electric ants?

If you live in Queensland and suspect you have found electric ants you must report them within 24 hours via an online form or by calling Biosecurity Queensland on 13 25 23. A nationally funded electric ant eradication program is in its final stages in 2021, so detections of any remaining outbreaks in north Queensland are critical.

If you live in Cairns or surrounding regions and have ants that might be electric ants, you can post them, along with your contact details and address, to the National Electric Ant Eradication Program at PO Box 652, Cairns, QLD, 4870 (just make sure the ants are dead).

Alternatively, you can request a property survey, by calling 13 25 23, or via the Queensland Government website. You can also phone for a collection kit and reply-paid envelope for submitting sample ants.

Outside Queensland, anyone who suspects they have found electric ants should phone the Exotic Plant Pest Hotline: 1800 084 881.

In places that have them, electric ants are a major social, economic and environmental problem. In Brazil, Florida and on Pacific islands they commonly live inside houses and sting residents. People are also stung on their swimming pools by ants that fall from trees on to the surface. This also happens in Cairns.

On islands in the Pacific, dogs and cats are commonly blinded by the ants, as well as suffering the pain of stings. Domestic chickens and wild animals are also blinded.

The ants hinder agricultural work by stinging fruit pickers and other farm workers. By tending and protecting scale insects and aphids, the ants increase sap-sucking bug densities on citrus and other crops, reducing fruit output.

Electric ants represent a threat to the tourism industry in Queensland because tourists can be stung, as they are in the Galapagos Islands.

Last but certainly not least, electric ants are a major environmental concern. They prey heavily on insects and displace other ant species. They are believed to have reduced lizard populations in New Caledonia and tortoise numbers in the Galapagos.