The stinging little fire ant has spread from the Big Island to Maui and Oahu, the state Department of Agriculture announced Tuesday afternoon, and officials have already ranked it as "the most serious insect pest" for the "foreseeable future."
"This is probably one of the most serious pests that we're dealing with in the state," said Darcy Oishi, acting plant pest quarantine branch chief. "It's ranked worldwide as one of the worst ants to get. I would trade for most insect pests (rather than) have this."
Infestations were found specifically on hapuu, or Hawaiian tree ferns, which were shipped on Dec. 11, officials said. The department is asking anyone who has recently bought hapuu logs or planters to place them in a plastic or garbage bag and seal it securely.
The little fire ant, which was discovered Dec. 23 at a garden shop on Maui, is shown in this photo. The state Department of Agriculture announced the discovery in hopes of stopping its spread.
Hawaii Department of Agriculture photo
Residents also should call the department's Plant Quarantine Branch in Kahului at 872-3848. The branch is open weekdays from 7:45 a.m. to 4:30 p.m.
Considered one of the world's worst invasive species, the ant was discovered Dec. 23 by a customer at a garden shop on Maui, officials said. The ant was reported to the Maui Invasive Species Committee, which sent specimens to department entomologists who confirmed the identification.
No shipments were believed to have been made to Molokai or Lanai, but officials are asking residents to call if they see any suspicious ants.
"It's serious when sales occur because it's so hard to detect," Oishi said. "Someone could have taken it home and a colony could be - at this moment -establishing itself.
"That's why we're going to the public now."
As of Tuesday afternoon, agricultural officials only knew of 11 plants, two stores and one shipping company that were infected by the ants. The names of the stores and the shipping company were withheld by the department, and officials believe there may be more companies and stores that were affected.
Kyle Yagi, plant quarantine supervisor of the Maui branch, echoed those concerns after observing a crate full of infested plants at one of the stores.
"It was pretty heavy," he said of the process where officials placed palates smeared with peanut butter inside the crate. "We put the baits out and you could see (the ants) on the baits, and there were a lot of sticks out there."
Agriculture officials do not know the extent of the infestation on Maui, but Oishi said Oahu is in a "much worse situation" where at least 50 infested plants could potentially have been sold.
"I never had to deal with a situation like this with the sheer volume with what has been moved and sold," he said. "We're still trying to get a hold of numbers of nonpropagated and propagated materials . . . Both could spread so we're tracking down all the people that" supplied and bought the plant.
The plant can be sold as a fern for planting and is popular as a stump for making orchid media, Oishi said.
Agricultural officials revisited the two stores on Friday and treated the surrounding areas with pesticides. The two stores that were affected have been told not to sell any plants, and agricultural officials are following up with two more plant retailers.
"Unfortunately this happened during Christmas so we're a little short on staff," Oishi said.
The pale orange ant that hails from South America is only 1/16th of an inch long and moves slowly, unlike the tropical fire ant already established in Hawaii. Colonies can be found on the ground, trees and other vegetation, and can "freely move into homes" and "completely overrun a property," an announcement from the department said.
"When this ant gets established, it can quickly become the dominant ant species," Oishi said. "It can severely affect our way of life and the health of our animals so the impacts of it are multidimensional."
The invasive ants are attracted to moisture and will crawl into the eyes of animals and sting them after the animal reacts, Oishi said. There has been an increase in blind cats and dogs on the Big Island due to the ants.
For humans, the ants can produce painful stings and large red welts on the skin.
The tiny ant was first detected in the state on the Big Island in 1999. Surveys determined that the ant was on the east side for several years before detection and was widely distributed in the Puna area, the announcement said.
Since then, agricultural officials have been concentrating on preventing the invasive species from jumping islands, in addition to dealing with damages that could reportedly reach $170 million a year.
"It is a problem that the Big Island will have to live with," Oishi said. "It is beyond the point of eradication and would require hundreds of millions of dollars" to fix.
Little fire ants have reached Maui in years past, though, as they did in October 2009 at a Waihee farm.
The department reports that eradication efforts appeared to have contained the infestation and that the area is continually monitored by department staff, Maui County workers, MISC staff and private pest control operators. Volunteer monitors also have been trained by the department to assist in recognizing and reporting possible infestations, including surveys at "high-risk areas" on Maui, the news release said.
For more information on the little fire ant and its history in Hawaii, visit hdoa.hawaii.gov/ pi/files/2013/01/npa99-02-lfireant.pdf.
* Chris Sugidono can be reached at email@example.com.