The browsing ant (Lepisiota frauenfeldi) is a concerning ant from the Mediterranean region whose domineering supercolonies displace native ants and most other insects from the sites they occupy.
Browsing ant. Photo: Copyright State of Queensland through the Department of Agriculture and Fisheries
Browsing ants are tiny and difficult for the non-expert to distinguish from other tiny ants. The purpose of this page is not to provide definitive identification but to rule out enough alternatives that an approach to the authorities is justified. Look for the following characteristics:
- Ants with a uniform shiny dark brown colour.
- The antennae and legs are long for the size of the ant, though not longer than the ant.
- The ants are all the same size rather than coming in castes of different sizes.
- They run around in a haphazard manner when disturbed.
- They teem over someone who disturbs them but do not sting.
The following feature is very helpful, but requires a good magnifying glass:
- The thorax when viewed from above has a dramatic constriction. It is widest above the first pair of legs (where they join it), then it becomes very narrow, before widening again, though not as much, above the other legs.
The browsing ant has a thorax in an hourglass glass shape when viewed from above. Photo: Shannon Hartman | www.antweb.org
Browsing ants teem over anyone who disturbs them. Photo: Western Australian Department of Primary Industries and Regional Development
Workers are about 3-4 millimetres long (not including legs and antennae).
Behaviour and location
Browsing ants favour sunlit settings, where they make loose nests, often in bare ground or under timber or mulch or rubble. They will also enter houses and sheds, using crevices in these as nest sites. Like many ants they are attracted to electrical currents and will nest in electrical boxes. They also climb trees.
They can occur in very high densities, of thousands on a square metre of ground, and this helps distinguish them from some ants. They are especially likely to arrive near a port or in an industrial zone that receives imported goods, but the finds made in Perth and Jabiru show them to be capable of turning up anywhere.
Browsing ants can be confused with a range of ant species found in Australia, two of which are featured as examples.
Argentine ants (Linepithema humile) tend to be smaller (2-3 millimetres long) and lack a narrow waist. Their legs and antennae are shorter. They do not walk in a haphazard way. They are a common nuisance ant from South America.
The Argentine ant lacks a narrow waist. Photo: Natasha Wright, Braman Termite & Pest Elimination | Bugwood.org
Argentine ants don’t have especially long antennae or legs. Photo: Whitney Cranshaw, Colorado State University | Bugwood.org
Black crazy ants (Paratrechina longicornis) are dark with long legs and antennae, and like browsing ants they move in a haphazard (crazy) way. They tend to be smaller (2.1 to 3 millimetres long) and lack a constricted waist. They are an introduced species, probably hailing from Africa, that is now widespread in the northern half of Australia, where they rate as a nuisance but not as an environmental threat.
Black crazy ants. Photo: Eli Sarnat, PIAkey: Invasive Ants of the Pacific Islands, USDA APHIS PPQ | Bugwood.org
Browsing ants are not harmful to people. They cannot sting. A few of them can be scooped into a container and frozen for later identification by experts.
Who to tell
Think you’ve found a browsing ant?
Phone the Exotic Plant Pest Hotline: 1800 084 881. You will be put in touch with the Department of Primary Industries or Agriculture in your state or territory.
If you do not receive a satisfactory response within a week email us via our contact form.
Browsing ants are an emerging concern because they operate like other invasive ants, such as yellow crazy ants, by forming domineering colonies that displace other insects including other ants. Like many ants they protect and ‘farm’ sap-sucking insects such as scales, mealybugs and aphids, increasing their densities on plants, leading to reduced plant health.
In recent years they have been travelling more freely. They are readily transported in shipping containers and cargo, and in soil, mulch, fertiliser and pot plants.
In 2014 browsing ants were detected around Perth Airport, and they then turned up in several Perth suburbs (Belmont, Welshpool, Kewdale, Bullsbrook, East Rockingham) and in Fremantle, probably representing two (or more) arrivals from overseas.
In 2015 they were found around the port area of Darwin, and from here some were accidentally carried to Jabiru township in Kakadu National Park.
In 2019 they were detected at a container yard at the Port of Brisbane. From each of these locations they have been eradicated or eradication is underway, so there is hope they will not establish in Australia. But further arrivals are inevitable, and they will spread rapidly if they are not detected early on, so vigilance from the community is essential.
- Australian efforts to eradicate this ant: National pest & disease outbreaks
- The ant is a concern for the Pacific region: Pacific Ant Toolkit