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Fire ant infestations fought in East, South Maui

“Little fire ant infestations expand in size fairly slowly on their own. It’s with people moving them around that they are spread long distance,” said Lissa Strohecker, Maui Invasive Species Committee outreach and education specialist.

Invasive species officials estimate that 2 to 3 acres in Kaeleku in East Maui are infested with little fire ants and treatments of the area will be ongoing for a little over a year.

The Kaeleku infestation is one of two recently discovered on Maui in the first week of December. The other infestation was found at a South Maui plant nursery.

Ant-infested material was treated, and the nursery voluntarily held the material for 30 days. The material will be resurveyed after 30 days to be sure the ants are gone, said Lissa Strohecker, Maui Invasive Species Committee outreach and education specialist.

Last week, MISC held a community meeting in Hana to inform and educate residents on the latest infestation.

“The community is concerned, and rightfully so, and we discussed what they can do to keep the little fire ants from showing up on their property,” Strohecker said.

This can be done by quarantining and testing any material brought home that has been stored outside. This includes common things such as soil, mulch, compost and potted plants.

In March 2016, an alert Maui landscaper discovered that little fire ants had hitchhiked to the Valley Isle in a pallet of asphalt shingles that had arrived from the Big Island. The delivery had been headed to a Hana residence.

Quick reporting by the landscaper and an immediate response by MISC staff eliminated the ants within 24 hours of their arrival.

As for the Kaeleku infestation, workers are still determining its full extent.

Strohecker said there is an intermittent stream that runs through the infestation and workers want to survey the makai portion thoroughly to make sure ants have not moved down the stream.

The ants apparently came from the more than 20-acre infestation in Nahiku, where they had been on the property for years before they were recognized as being present, she said. Kaeleku and Nahiku are about 8 miles apart.

“Little fire ant infestations expand in size fairly slowly on their own. It’s with people moving them around that they are spread long distance,” Strohecker said.

She said it’s hard to say how long the ants have been on the Kaeleku property, but given the infestation’s size, it’s likely they’ve been there for several years.

“This underscores the fact that it’s the infestations we do not know about that pose the greatest threat,” she added.

MISC reported that a resident on the Kaeleku property claimed to have been stung for several months while working outside but had assumed it was common skin irritation from stinging vines.

Brooke Mahnken, the little fire ant coordinator for MISC, added that the resident on the Kaeleku property has ties to the Nahiku area where the other infestation was found.

The MISC Hana crew surveyed the Kaeleku property immediately. Crews are surveying all locations where material from the infested property in Kaeleku had been moved and to date no other populations have been found.

Mahnken said that the ants, if left unchecked, do not expand at a rapid rate on their own naturally. According to the Hawaii Ant Lab, a study in Mexico showed that the little fire ants may move only a few yards per year, he said.

The ants move with the queen that relocated only when a population is saturated, he said.

As for the South Maui infestation, it was found by state Department of Agriculture inspectors who were following up on recently discovered shipments of little fire ants in plant material from Hawaii Island. MISC crews and state agriculture officials determined the infestation to be in about an acre.

The infested material was quarantined and treated, and the nursery is open for business.

A survey of the nursery for the ants was done on Jan. 29.

Strohecker said they are concerned that ants have been present at the nursery for sometime prior to detection, possibly years.

* Melissa Tanji can be reached at mtanji@mauinews.com.