The Argentine ant (Linepithema humile) is one of the real nasties of the insect world – capable of forming ‘super colonies’ of billions of individuals that can literally cover thousands of kilometres.
The Northland Regional Council this week begun distributing several hundred copies of a Proposed Pest Management Strategy for the ant and is seeking public feedback on it until Friday 12 May.
Lisa Maria, a Land Resources Officer with the Northland Regional Council, says the Proposed Strategy aims to contain, where feasible eliminate, reduce and restrict the distribution of Argentine ants - and several other pest ants - in Northland.
Ms Maria says Argentine ant is a light to dark honey-brown colour, about 2-3mm long and was first recorded in Auckland in 1990. It is thought to have arrived in Northland via potted plants, freight or wood.
Argentine ants are now found in or near populated areas throughout the region and are unlikely to ever be totally eradicated.
However, Ms Maria says it is vital that the spread of Argentine ant is limited as much as possible for a whole host of reasons, including environmental, economic and health.
“Unchecked, Argentine ants can form colonies of unbelievable size and the World Conservation Union has classified it as among the ‘100 of the World's Worst Invasive Species’. Around the Mediterranean and Atlantic coasts, a single Argentine ant colony has been recorded spanning 6000 (subs: crrct 6000km) kilometres.”
The voracious ants travel in multiple lines of up to five wide, invading houses, swarming over foodstuffs and infesting gardens. They can invade beds at night seeking moisture and can swarm over sleeping babies.
“Some people are sensitive to their bite and the ants also have the potential to spread disease.”
Ms Maria says overseas, Argentine ants can affect the profitability of the horticultural and agricultural sectors because they protect honeydew-producing insects such as aphids and scales.
“The ‘farming’ of these insects by Argentine ants allows the insect populations to increase to economically damaging levels.”
There are overseas reports of the ants invading beehives and removing the honey. They are also known to swarm into birds' nests, caged birds and to attack the newborn chicks, also prompting fears for the young of native species like kiwi.
Argentine ants also compete very effectively with all other insects, both by fighting and by monopolising all available food sources.
“Unfortunately, Argentine ants are also very difficult to tackle, with only one commercially-available bait able to control them and which is best used between December and April. They don’t respond to common household sprays and baits – and can even increase in numbers if the wrong bait is used.”
Ms Maria says ‘human-assisted dispersal’ is the main method for spread of Argentine ants; otherwise they spread very slowly, typically only about 150-metres annually from their main nest.
She says people can help prevent the spread of Argentine ants by thoroughly checking pot plants, compost or other garden material before moving them to another area. Similarly, vehicles, caravans and trailers at infested properties should be checked before travelling.
There are also some precautions people can take around the home to try to reduce infestations, including:
- Putting pet food bowls on a tray of water to stop ants accessing it
- Cleaning kitchen and other surfaces with lemon juice, soapy water or diluted eucalyptus or tea tree oil
- Trimming trees near homes to prevents ants gaining access to windows or a roof
Xstinguish argentine ant bait is now available on the TradeMe website: www.trademe.co.nz. A search for "DIY pest control" will take you directly to the correct area. Alternatively you can phone the DIY shop in Auckland on 09 486 4411.