Different species of ant are more or less susceptible to this standard treatment and some may be difficult to eradicate. Argentine Ants, pose particular difficulties but can be controlled by following the plan below.
How to identify Argentine Ants
Because they are so small, the best way to tell Argentine ants from other ants is by their colour, trails and lack of smell when squashed. The wingless worker ant (most commonly seen) is light to dark honey brown and 2-3mm long (most other common household ants in NZ are black). Argentine ants are highly active in searching for food. Their trails are often five or more ants wide and can travel up trees and buildings. Most other species of ants in NZ don't tend to climb trees (White Footed Ant being an exception), and would not have such strong trails unless they were moving a nest (in which case you would see ants carrying their eggs). Argentine ants look very similar to another pest species called Darwin Ant. However, if you squash an Argentine ant there is no strong formic acid smell as there is with some other ants including Darwin Ants.
Where have they been found?
Argentine Ants were first found in Auckland in 1990, more recently they have been found in Northland, Waikato, Bay of Plenty, Hawke's Bay, Wellington, Nelson, Blenheim and Christchurch. Although they breed prolifically they do not swarm (fly off to establish new nests). This means they do not spread very rapidly (except when foraging queens are carried in boxes, pot plants, vehicles etc.). But when a site is infested it will have a very high number of ants and colonies. Their natural rate of invasion is a few hundred metres per year. However, their main way of spreading into new areas is via transported nests and/or queens, which often happens when plants or other garden materials are moved. The foraging queen ants and workers may also be transported in vehicles. Argentine ants seldom or never disperse in winged form.
Why are they a threat to NZ?
Left unchecked Argentine ants will become a major household and garden pest. Their huge numbers (up to six nests per square metre) mean a huge appetite and they will utilise just about any food source they can find. They have even been known to make their way into refrigerators, microwaves and screw top jars! In California they are considered to be one of the worst household pests.
Argentine ants threaten native invertebrates as they are very aggressive and killing and driving off other insects. They climb trees and can kill baby birds in the nest. They are also active foragers and compete with other species that feed on honeydew or nectar such as insects and birds.
Argentine ants 'farm' populations of aphids, scale insects and other pests that produce honeydew. The Ants protect the sap sucking insects from predators and will even move them to new plants or to new parts of the plant. This is a particularly serious threat to organic grower and those growers using integrated pest management, who rely on predators to control these pests. Argentine ants have also been reported to feed directly on fruit crops and their mass numbers can damage flowers thereby reducing fruit set. They are one of the worst citrus pests in Australia, and a serious pest of viticulture, avocado and tomato crops.
The scientific name for Argentine Ants is Linepithema humile.
To get rid of Argentine Ants carry out the Kiwicare 1-2-3 Bait-Barrier-Destroy program.
- Bait > Use many small amounts of NO Ants Gel Bait
where you see ants or have seen them in the past. Workers feed on the bait and take it back to the nest to feed and kill the queen(s) and larvae. Replenish the bait regularly until you see no more (or very few) insects feeding. Only then should you use spray insecticide to eradicate the nests and to act as a barrier to further infestation. Ants are very sensitive to strong chemicals. All dishes or containers used to hold bait should be rinsed well with clean water and dried before use. A great alternative is to use a strip of masking tape and squeeze the bait on top. The tape will hold the bait in place and can be easily removed.
Stop them farming > Argentine ants may be 'farming' aphids and scale insects on trees and plants in your garden. Spray these plants with PLANThealth Insect Hit and apply LawnPro Lawnguard Granules around the roots.
- Stop them with barriers > Use Kiwicare NO Bugs Super
, NO Bugs Indoor
or NO Ants Barrier Spray
around tree trunks to discourage ants, especially where birds are nesting. Thoroughly spray/paint all entry points into the home with NO Bugs Super
or NO Ants Barrier Spray
and sprinkle LawnPro Lawnguard Granules
as a barrier around buildings.
Keep dry > Reduce moisture sources (e.g. leaking taps, irrigation) as Argentine ants prefer moist conditions. Keep your roof and sub-floor dry and well ventilated to discourage ants from nesting there.
- Deny them a nest site > In winter you may be able to follow the ant trails back to the colony. If you can find this colony you may be able to kill it with NO Ants Ant Sand . NO Ants Ant Sand will not to encourage the colony to 'bud' i.e. move to a new nest site or sites.
Did you know
Boric acid and Borax can be effective against Argentine ants, once the bait has reached the Queen. Until the queen and her replacements are controlled, the colony will continue to grow.
Argentine ants differ from local species as they are aggressive and drive out or kill other resident insect species including ants. They form super-colonies in winter to survive the cold, and then bud-off into new colonies in the spring. They also breed in far higher numbers, and have multiple queens in the nest. Because of this, their nest are far harder to kill than other species. NO Ants Gel Bait will control them, however due to the other queens present in the nest, it will take some time to eradicate. Persistence and patience are the key. As long as the ants are taking the bait, then eventually some will get to the queen and kill her. However, then her replacement will become active, and baiting must continue till she is also dead, and so on till the supply of queens is exhausted.
Kiwicare's NO Ants Liquid Bait and NO Ant Gel Bait active ingredient is Boric acid and Borax and are ideal to use. Boric acid and borax are slow acting poisons, but slow acting toxins must be used, to allow time for the bait to be introduced to the queen. If a fast acting poison was used, i.e. permethrin, you would certainly kill the workers and foragers, but no toxin would get to the queen, who will keep on laying eggs.
Stick masking tape on delicate surfaces and then apply bait onto the masking tape. This protects the surface and allows easy removal.
Tips for controlling Argentine ants around your home
- DO NOT spray generally for ants before baiting and putting barriers in place, as this may encourage new nests to 'bud off' from the main colony; spreading the problem. Use non-repellent NO Ants Ant Sand on nest sites to prevent budding.
- Keep food from ants > Remove or securely store food that is favoured by ants.
- Follow the general ant control advice on the Ants Page
- Trim trees near your home to reduce ant access to your roof or window areas.
- Reduce moisture sources (e.g. leaking taps, irrigation) as Argentine ants prefer moist conditions. Keep your roof gap and sub-floor dry and well ventilated to discourage ants from nesting there.
- Where ant trails enter your house spray with a permethrin based spray such as Kiwicare's NO Ants Barrier Spray ready to use trigger spray. It will be necessary to reapply barrier after rain fall (if outside) or every week (if exposed to direct sunlight). Thoroughly spray all entry points into the home.
- In winter you may be able to follow the ant trails back to the colony. If you can find this colony you will be able to kill it with NO Ants Ant Sand.
- Some ants 'farm' aphids and scale insects for sweet secretions and it worth treating your plants with PLANThealth Insect Hit to control these sapsucking plant pests and deny the ants their food supply. LawnPro Lawnguard Granules or PLANThealth Insect Hit Granules are useful in areas of garden where ants are a nuisance and as an additional barrier around a house or other building. The granules are sprinkled onto soil and gravel surfaces where ants are travelling and then watered in to take the insecticide deep into the soil, forming a curtain barrier.
Ants in the Garden
Many will know about ants as pests when they come indoors, and lines of them are found trailing into our larders and over kitchen work surfaces. But when ants are outside in the garden they may not be recognised as a pest.
How to Use LawnPro Lawnguard to Control Soil Dwelling Pests
How to use LawnPro Lawnguard to control grass grub, porina, cutworm, ants and other soil dwelling pests.
Deals with Argentine Ants
View all products
- LawnPro Lawnguard
- NO Ants Ant Sand
- NO Ants Bait Stations
- NO Ants Barrier Spray
- NO Ants Liquid Ant Bait and Stations
- NO Ants Nest Killer Gel Bait
- NO Bugs Indoor
- NO Bugs Super
- Plant Health Insect Hit Granules