How to Control Argentine Ants

HOW TO CONTROL ARGENTINE ANTS

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The only effective method for control at present is to hand lay baits using Xstinguish™ ant bait. The toxic bait is carried back to the nest and fed to queen, young and other workers. 

The bait has no effect on humans, cats or dogs. It contains fibronil which is the same ingredient used in flea control for cats and dogs. However, fipronil is toxic to fish and should not be used close to stormwater channels such as gutters, or close to streams or other waterbodies.

Antstop G can be used to prevent re-infestation in an area that has already been treated. This product kills ants that have walked over treated ground, but does not kill ants in the nest.

Spraying using other ant control products may make the argentine ant problem worse by causing colonies to split. The ants can detect the poisons and will move queens and eggs to new uncontaminated areas.

Contact a professional pest control company for assistance or to obtain the bait Xstinguish™. 

There are no known biological agents for use against Argentine Ants.

Getting rid of every last ant

Well-planned and executed baiting treatments can result in dramatic reductions in ant populations. But the tricky bit is always killing the last 1% of the population - that is where most of the budget and effort goes. Argentine ants are no exception to this rule.

Think of Argentine ants like rats and mice – in most places, control is the most practical option, but in some locations, like offshore islands, complete eradication may be feasible. 

However, re-infestation can occur. So once you’ve got rid of the ants from an area, make sure you are not transporting ants back in. Sometimes a quarantine area may be useful – especially if you are transporting risky materials (horticultural products, soil, etc) to and from your now-clean site.

The Department of Conservation decided to eradicate Argentine ants, when they hitched a lift on building materials to Tiritiri Matangi Island nature reserve in the Hauraki Gulf. They are close to achieving this, and continue an ongoing monitoring and toxic baiting programme.

LARGE SCALE CONTROL AND ERADICATION PROGRAMMES

Embarking on a large scale programme of control or eradication is a major decision. The best results will be achieved through an approach that incorporates aspects of inspection, identification, containment, and public education.

You will need:

  • Careful planning
  • Adequate resources (staff & financial)
  • Public cooperation
  • Political commitment
  • Specialists (ant ecology, surveillance, baiting, monitoring)
  • Trained contractors/team leaders
  • Operational management
  • Good communication (media & public)

The Integrated Pest Management (IPM) approach has been integral to the success of control operations in Tauranga (Environment Bay of Plenty) and in Christchurch (Department of Conservation, ECan and Christchurch City Council).

Environment Bay of Plenty has included Argentine ants as an ‘eradication’ pest animal in their 2003-08 Regional Pest Management Strategy (offsite link to www.ebop.govt.nz), and Auckland Regional Council is proposing to add them to their Strategy, giving them the statutory powers they need to effectively carry out their control operations.

How to monitor the extent of infestation

Once Argentine ants have been positively identified at a new site, you will need to work out the extent of their infestation. 

As small nests are hard to find, treated areas should be subject to ongoing monitoring.

Landcare Research is conducting preliminary trials in Auckland to compare baiting with different detection techniques. Early results indicate the non-toxic monitoring version of Xstinguish™ bait is better than pitfall traps at detecting Argentine ants at low densities.

The best time to monitor, using either attractant baits or hand-searching, is during warm, dry weather, when the ants are most active. Summer is ideal for this. But remember that ant activity will cease when the ground temperatures gets over 26 degrees Celsius. So on hot days, monitoring is better done early morning or late afternoon.

Do the public have a role in ant control?

These ants rely on human dispersal for rapid movement, so public awareness of the problem will reduce the risk of spread, and help support your control operations.

A good education program involves the media, and needs to:

  • Provide accurate, non-technical and easily accessible public information.
  • Avoid promising over-optimistic outcomes.
  • Provide a list of knowledgeable persons who can be (and are willing to be) contacted for further information.

In particular, garden centres and nursery suppliers should be made aware of the problem and be looking out for these ants. 

Likewise, staff and pest control operators who work in warehouses of freight moving companies should also be on the lookout for Argentine ants.

Christchurch City Council has produced an Argentine ant communications plan, as well as some excellent public awareness support for Argentine ant control in that city.

What is the best control method?

The first step in a toxic baiting programme is to positively identify the ant, followed by a delimiting survey to determine the size of the infestation. This survey is particularly important as it lets you accurately determine the operation’s cost and its likelihood of success.

The infested area needs to have an external buffer added to the treatment zone, to pick up any undetected nests that would otherwise go untreated.

When undertaking a large scale baiting operation, remember:

  • Monitoring is highly desirable before baiting to assess ant numbers and after treatment to assess effectiveness.
  • Ensure stakeholders and affected landowners are given adequate notice of the operation (allow several weeks where landowners’ permission is required).
  • Plan baiting to coincide with high levels of ant activity (mid summer).
  • Ensure soil temperatures are 15 C or better (especially important in southern areas).
  • Bait all infested areas on the same day to achieve the best results.
  • Very large areas can be broken into smaller areas, using physical barriers such as roads, streams and buildings; these can be baited on different days.
  • Lay baits by hand, about 2 metres apart from each other, in a grid pattern (in bark gardens, lay baits 1.5 metres apart).
  • Baits containing fipronil (e.g. Xstinguish™) are laid in 1 gramme ‘blobs’
  • Aim to lay approximately 3 - 3.5kg/ha bait for the average residential section. Double this bait density for hilly/rough/untidy/ geothermal terrain, and reduce it for industrial sites with large areas of tarmac.
  • Baiting is labour-intensive, and will require 4 hours/hectare on flat land with easy access and up to 18 hours/hectare on steep hillsides with difficult access.
  • Do not lay bait indoors.
  • Do not lay baits in street gutters or within 3 metres of a watercourse.
  • Re-baiting will be needed about 6-8 weeks later (late summer) to kill any survivors and any ants that have subsequently hatched.

After a toxic baiting programme, do an accurate survey to locate surviving nests. These can be treated to prevent re-infestation.

Use Antstop G on boundaries, to help stop ants from re-infesting baited areas if neighbouring properties are infested but did not get baited with Xstinguish™.

How to use baits effectively

Toxic baiting uses a food these ants love that incorporates the toxin in it. The toxin concentration is such that any adverse effects are delayed until it has been fed to larvae, queens and other ants. It must be present in sufficient quantity to kill all ants in the nest. The queen is the primary target of the operation.

Xstinguish™ bait (containing fipronil)

Xstinguish™ bait was developed by the Western Australia Dept of Agriculture and brought to New Zealand by Landcare Research.

It is registered for use in New Zealand and available from Bait Technology Ltd (contact info@baittechnology.co.nz or phone Flybusters/Antiants at 0800 83 70 70).

Xstinguish™ bait is highly attractive to Argentine ants, and has been used extensively to control these ants in the Auckland urban environment, as well as by the Department of Conservation for control on Tiritiri Matangi Island and on the edges of a kiwi sanctuary near Whangarei. The bait has also been used successfully in Tauranga, Rotorua, Nelson and Christchurch.

Xstinguish™ bait is currently available in a 325 gm tube that is applied with a caulking gun. This is usually sufficient to treat 2-3 residential properties. A smaller 60 gm home pack is also available.

The toxic ingredient in Xstinguish™ bait is fipronil. This active ingredient also used in cat and dog flea treatments, and in cockroach bait. 

At the very low concentration level of fipronil used in Xstinguish™ bait, the Environmental Risk Management Authority (ERMA) does not classify the bait as a harmful substance, having no effects on human health, or the health of cats, dogs or honeybees.

However, fipronil is toxic to fish and aquatic invertebrates, so baits should be kept clear of street gutters, and should not be laid within 3 metres of a watercourse or waterbody. 

Antstop G (Chloropyrifos Granules)

This granulated product is a water-activated, slow-release toxin which kills insects by contact after they walk over the treated ground. 

It is not considered an effective control agent by itself, as the only way Antstop G could kill the nests would be if it was directly applied to each and every nest.

Antstop G is best used as an ‘ant barrier, protecting an area from re-infestation, rather than as a first line of attack.

For more information about suitable baits and baiting methods for Argentine ants, contact Bait Technology Ltd – email: info@baittechnology.co.nz or phone 09 489 7090.

Page last updated: 18 June 2008