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Published: 2006-01-25 00:00:00

Environment Waikato contractors will be visiting Morrinsville next month to check on the spread of Argentine ants, a voracious insect pest.

Argentine ants are aggressive insects and, although they are not poisonous, they can bite people. They have been known to make their way into microwaves, refrigerators and screw-top jars, and are capable of killing other insect species and earthworms.

The pests were first discovered in Auckland in 1990 and are now established as far south as Christchurch. They are thought to have been spread via items like containers, pot plants, household goods and pallets. Freight yards are often focal points for their dispersal.

Morrinsville has the largest Argentine ant infestation in the Waikato region.

Responding to calls from the public, Environment Waikato commissioned a survey of Morrinsville in 2003 to determine the extent of the problem. The pests were found spread across a 60 hectare area in commercial and residential parts of the town.

As a follow up to that work, Environment Waikato will be undertaking a second survey in Morrinsville in early to mid February, providing the weather is hot and dry, in an effort to discover how far the population has spread.

“We want to know how widespread the ants have become in Morrinsville and investigate a number of control options,” biosecurity operations manager Peter Russell said.

Contractors will be laying traps lured with non-toxic ‘feed’ bait to capture ants along the main arterial routes leading out of Morrinsville. They will be collected for identification and their new distribution area in the township will be determined.

Argentine ants have been declared a ‘potential pest’ under Environment Waikato’s Regional Pest Management Strategy.

“While eradicating Argentine ants in New Zealand is not possible due to how far they’ve spread, there is a new bait available that is very effective in controlling these pests in localised situations,” Mr Russell said.

The bait, Xstinguish, is marketed by Auckland company Bait Technology Ltd. Members of the public wishing to obtain it can call Flybusters on 0800 83 70 70.

The most commonly seen wingless worker Argentine ants are light to dark honey-brown in colour and 2-3mm long. They often travel in trails of five or more wide. In contrast, ants commonly seen in New Zealand houses are black in colour and slightly larger.