Residents urged to act to stop ants
The number of properties infested with Darwin's and Argentine ants in Nelson is continuing to increase as the invasive pests continue their march across the city.
There are now 2540 properties in Nelson and Richmond that have Darwin's or Argentine ants. This is up from 2012 properties last summer, and 895 five years ago.
People who live on properties known to have the ants are asked to be vigilant and help slow their spread, particularly to stop the pests moving to the region's offshore islands and other special places.
People should check pot plants do not contain colonies before moving them.
Caravans, trailers, vehicles and boats that had been parked up for periods should also be checked for the ants before they are shifted off the property.
Nelson entomologist Richard Toft urges people to check that there are no queen ants, or worker ants carrying larvae or pupae in boats, caravans or vehicles before they are moved.
He said new infested areas were largely a result of infected areas expanding into neighbouring properties.
As the number of properties infested grew it was more likely that new areas would pop up outside areas already known to have the ants.
Argentine ants continue to be the biggest problem in the region. There are 2265 properties known to have Argentine Ants. Of these, 1521 are in Nelson and 691 in Richmond.
Both Darwin's and Argentine Ants are small and brown, and can quickly become household and environmental pests.
Argentine ants were first found at Port Nelson in 2001 and are considered to be one of the world's worst invasive ant species.
They rapidly increase in numbers, form super-colonies and are difficult to eradicate. They can spoil outdoor activities in backyards and can also affect the health and growth of garden plants.
Darwin's Ants produce a strong smell when squashed.
Tasman District Council's biosecurity co-ordinator Lindsay Vaughan said it was disappointing to see the extent of the spread of the ants in the region, but the councils believe the rate of spread is slowing.
However, many residents have found treating their whole section too expensive.
Lindsay said the control programme for properties with Darwin's Ants has been completed, but residents dealing with Argentine Ants in Nelson were required to bait for those ants over the next two weekends.
A co-ordinated approach to baiting is required if it is to be the most effective way to stop re-invasion from neighbouring properties. Residents in southern Nelson and Stoke are asked to bait this weekend, or, alternatively, on the first fine evening afterwards.
Wakapuaka residents, The Wood residents and those with infected properties in Richmond should bait on February 15 and 16 or the first fine evening that follows.
Lindsay says there are different treatment options available and properties known to have the ants will have received a letter containing treatment information from the councils.
He says residents can use X-It spray which is $51.75 for 225ml, Bi-force granules which costs $11.60 for a 500 gram shaker and Xtinguish bait which costs $60 to $70 for 325g cartridges.
All products can reduce the number of ants, but will not get rid of them completely.
Lindsay says many people like the spray and granules because they stop re-invasion of the ants for the short to medium term.
He said because the products were contact insecticide people should use the spray in a targeted way and not cover their whole property with it.
Xtinguish will control the ants, but is not as effective at stopping re-invasion.