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Treatment of fire ant nests

Two types of treatment are used to treat Fire ant nests; baits, direct nest injection (DNI) or a combination of both.

The National Red Imported Fire Ant Eradication Program will determine the best treatment strategy for your property or work site. They will consider:

  • public safety
  • season and temperature
  • location.

There is no cost to you when our program officers treat your property.

If our program officers suspect fire ants when they visit your property, they may treat the nest/s. In most cases, this will be in the form of bait treatment — applied in the immediate vicinity of the nest/s.

A notice will be left advising of the treatment actions taken.

If fast acting bait is applied, you should notice the ants die off in a matter of weeks.

If a slow acting bait is applied, a program officer may be in contact to schedule a follow-up DNI treatment.

If you cannot or do not want to wait for the program to treat your property or worksite, you may choose to Self-manage treatment.

Fire ant baits and how they work

Fire ant bait is made up of small pieces of corn grit (about 1–3 mm in size) soaked in soybean oil. Two types of bait are used depending on the location of the nest:

  • Fast acting bait — contains indoxacarb or a combination of hydramethylnon and pyriproxyfen. All three of these active ingredients are commonly found in cockroach baits or flea collars.
  • Slow acting bait — insect growth regulator (IGR) containing S-methoprene or pyriproxyfen which are widely used in mosquito control programs or dog and cat flea collars.

Both products are low-toxicity and when used according to the conditions on the relevant product labels and Australian Pesticides and Veterinary Medicines Authority (APVMA), are not harmful to humans or most vertebrate animals. After the baits are distributed, they break down in a matter of days.

Fast-acting baits cause a noticeable reduction in nest activity in 1–4 weeks and nest death soon after. The active ingredient is circulated around the colony via the worker ants, leading to the death of the worker ants, larvae and queens.

If the ants are still active after 5 weeks from fast-acting bait application, please contact the program to discuss the next treatment step, which may involve a direct nest injection.

Slow acting baits break the reproductive cycle of the queen and prevent new ants from maturing into adults. After the last adult workers have died (approximately 2–6 months), the queen is effectively starved as there is no one left to feed her and the nest will naturally die out.

Direct nest injection and how it works

DNI is generally used in instances where public or animal safety needs to be considered. DNI involves flooding the fire ant nest and ant tunnels with a registered insecticide known as fipronil. Fipronil is effective at very low application rates, of 25mls to 100ltrs, and is often used in termite control programs.

The liquid chemical is odourless and non-repellent to the ants. When applied the ants are unaware of its presence and eventually contact or ingest the insecticide. Within 3–4 weeks the colony is greatly affected, and within 8 weeks most of the ants will have died.

You will need to give the program permission if your property is scheduled to receive DNI treatment. A form will be provided to you by program officers.

What to do after treatment

For treatment to have the best chance of success, you shouldensure:

  • after DNI, a one-metre area around each mound remains undisturbed for at least 7 days. You should not mow, dig, water or lay new turf in the area around the mound.
  • after the bait treatment, the ground remains undisturbed and is not watered for at least 24 hours, preferably 48 hours.

Apart from the above you are free to enter the treated area immediately after bait treatment and 24 hours after DNI. Unaffected areas of your property or work site may continue to operate as normal.

Restrictions apply to the movement of materials that may carry fire ants. This includes, soil, mulch, animal manures, baled hay or straw, potted plants and turf. Before moving materials that could carry fire ants, please review the biosecurity movement control restrictions.