Invasive Argentine ants difficult to eradicate
Environment Bay of Plenty is changing the way it deals with Argentine ants, one of the world’s most widespread invasive ant species, recognising that eradication is no longer feasible.
“The regional council will continue to provide ant identification services and advice on Argentine ant control and will only become directly involved in control operations where they threaten areas of significant community value such as high value biodiversity sites,” Environment Bay of Plenty Group Manager Land Management Warwick Murray said.
“Despite active surveillance and control of known Argentine ant infestations it is clear that eradication of this pest will not be achieved,” he said.
“Environment Bay of Plenty has spent significant time and money trying to eradicate known populations of the ant within the region but this has not been successful because of the difficulty in getting to every nest and keeping new incursions out of the region.”
He says the task is made even more difficult because Argentine ants are great hitch-hikers. “They establish nests in anything from potted plants and garden mulch to rubbish and recycling bins. There are currently 28 known sites in Tauranga, Mount Maunganui, Rotorua and Whakatane.
“Even if we were able to eradicate these known infestations in the Bay of Plenty, it would be highly likely that new arrivals will come in from neighbouring regions where control is not being undertaken.”
Environment Bay of Plenty has written to property owners in the region who live in areas known to have Argentine ants, advising them of the change.
Argentine ants are currently classified as eradication pest animals in the Bay of Plenty Regional Pest Management Strategy (2003 – 2008). This strategy is currently under review and as part of the submission process members of the public will be able to have their say as to what level of control they would like
to see for various animals, including Argentine ants.
If you suspect you have Argentine ants present on your property, collect a sample (freeze them overnight) and bring them to an Environment Bay of Plenty office for identification.
For more information on Argentine ants please go to www.envbop.govt.nz or ring 0800 ENV BOP (368 267) or visit www.biosecurity.govt.nz
Facts about Argentine ants
The Argentine ant is not poisonous and has no sting but can bite and may cause a mild irritation or localised skin reaction.
Argentine ant workers are small (2mm to 3mm long), and a uniform honey-brown colour, but can look brown/grey when foraging in urban areas. Most common household ants in New Zealand are black.
Argentine ants are a similar size and colour to some of our native ants, but unlike native ants which only live outdoors, Argentine ants can be found both inside and outside of buildings.
The ants eat a very wide range of foods and invade native ecosystems and displace native species. They produce multiple queens and can form huge super-colonies that extend for thousands of kilometres.
Argentine ants form distinctive trails that may be five or more ants wide, and they will often immediately walk straight over objects that are placed across their trails. Most other ants in this situation become confused for a while if objects are placed across their trails.
While it would be a very difficult operation to erradicate Argentine Ants from New Zealand or an affected region of the country, it is possible to eradicate them from individual properties and localised areas.
It requires a program of treatment beginning with the use of many small amounts of a suitable bait. Identify as many nest sites as possible. Take time to follow trails of ants. Place baits where ants are seen or have been seen in the past. Argentine ants prefer bait with higher protein levels such as Kiwicare’s NO Ants Gel Bait. The workers take the bait back to the nest where it will be fed to queens and larvae and reduce the colony size. However, it is unlikely to erradicate colonies because each nest contains multiple queens and the queens will move readily to set up new nests.
After baiting treat the nest sites directly with a residual surface insecticide or slow release granules such as NO Ants Outdoors or NO Insect Lawngard Prills from Kiwicare. This will kill nests and act as a barrier to re infestation. Baiting first will have reduced the numbers and the liklihood of spreading the problem when using sprays or granules/prills.
Set up a barrier around the property to stop ants returning from the surrounding area. The Lawnguard Prills slowly release insecticide into the soil and form a ‘curtain’ that will stop ants travelling both on the surface and through the soil.
Spraying areas where the ants have been seen with NO Ants or NO Bugs Super will also kill any ants that cross the treated surfaces but are more likely to act as a barrier as ants will tend to avoid treated surfaces.
Where insecticides are unacceptable Kiwicare produce an Organic Ant Barrier containing capsiacin that ants and other insects will avoid and not cross. this can be used around a house both inside and outside.
Thoroghness and persistance are the keys to controlling ants, particularly Argentinian Ants. Even when no more ants are seen it is important to maintain the barriers and protection from re-invasion.
You will find more information on the Kiwicare.co.nz website.