WAILUKU » A state program aimed at knocking back a toxic weed has released more than 10,000 Madagascan fireweed moths and larvae in the past year.

The weed control is in full swing, but it might take a decade to show noticeable effects on the fireweeds choking Maui pastures, officials told the Maui News.

The Department of Agriculture distributed 2,500 moths in Maui in March 2013. Farmers and ranchers have been cultivating the insects in cages for release onto their properties.

When unchecked, the weed crowds out plants that livestock eat, hurting cattle and goat farms.

Mach Fukada, a state entomologist and biological control specialist, focused his early efforts on showing people how to keep the moths alive. Since then, he has been monitoring progress by the larvae to establish themselves in areas with fireweed infestations.

It may take years to determine just how effective the program is, he said.

"Right now, I’d say it’s a little premature," Fukada said. "But I do see evidence of caterpillars and adult moths spreading very easily, and if everything’s working out as it should and they get established — then we’ll see what happens."

He has observed steady populations in Ulupalakua, so he has begun focusing on Pukalani, Makawao and Haiku. He said larvae have also been spotted on Kahoolawe, where fireweed has been established.

Some ranchers have been able to grow strong, steady moth populations. On other farms, wind and weather have prevented nascent populations from taking hold.