Chemical enlisted against
pesky Maui flies

Scientists hope pellets will quell
the swarms over Kealia wetlands

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By Gary T. Kubota
gkubota@starbulletin.com

WAILUKU >> Scientists are visiting Maui this week to determine the best way to apply chemical pellets that they hope will reduce the seasonal swarm of millions of flies in the Kealia Pond National Wildlife Refuge.

Scientist Martin Berg of Loyola University is scheduled to arrive today to supervise the application of the chemical methoprene and conduct more studies.

Residents living at the nearby Kealia condominiums and motorists crossing the pond have complained about millions of flies known as midges that seasonally rise in plumes like small tornadoes.

The swarms were so thick earlier this year that some residents say they were unable to eat outside their homes and had to clean their swimming pools and porches daily.

Gary Elster, president of Friends of Kealia, said residents are pleased that the U.S. Fish and Wildlife Service decided to take action to reduce the swarming.

Elster said in areas where the chemical was applied at Kealia, there was a 90 percent reduction in the number of swarming midges.

"We're hopeful that it will be repeated in the actual treatment," Elster said.

The alien insect, known as Polypedilum nubifer and found in Australia and some Pacific islands, has a body about half an inch long with wingspans about a quarter of an inch wide.

In 1998 a Bishop Museum entomologist estimated the number of mature maggots at 150 million to 200 million at Kealia.

Refuge manager Glynnis Nakai said the plan is to apply the chemical pellet methoprene in 110 acres of the 200-acre pond, in water 1 12 to 3 12 feet deep where birds are less likely to forage for food.

Nakai said based on testing at the pond earlier this year, scientists found methoprene -- which one researcher says has been used to control midges in Florida -- was effective in retarding the growth of midges at the larval stage and prevented them from growing wings and swarming.

Nakai said scientists will be selecting periods near the expected peak of the midge season to apply the methoprene because the chemical only is effective for about 28 days.

She said the refuge has bought 2,600 pounds of methoprene for about $96,000 -- enough for more than two applications, although it plans to apply the chemical once to an area.

Nakai said according to the study, methoprene had no visible impact on birds that frequent Kealia, including the endangered Hawaiian stilts and coots. She said the methoprene did not kill the larvae, allowing them to be used as a food source for birds.

She said scientists will be monitoring the effects of the application of methoprene probably through the end of March or April of next year.

Studies also will be conducted to determine the water quality and contents in an effort to determine why the midges appear in such high numbers in January and February. Additionally, questionnaires will be handed out to residents to determine their level of satisfaction with the results of the chemical treatment.

Nakai said there were heavy rains last November, and the midges were beginning to swarm in December, but the midges have not begun to swarm this year.

Federal funds for the chemicals and a $100,000 study came through special appropriations supported by Friends of Kealia and initiated by U.S. Sen. Daniel Inouye and U.S. Rep. Patsy Mink, Elster said.

Wellmark International of Illinois is selling the methoprene under the trade name Strike Pellets.