State agriculture officials got the go-ahead to introduce a moth to fight a fast-spreading weed toxic to cattle.

They're arctiidae moths and they’re the state's weapons of mass defoliation.

State agriculture officials have finally been given the USDA's OK to release the moth to combat the spread of fireweed.

The moth feeds on fireweed.  Because the plant has no natural predators in Hawaii, it's the last hope to control the invasive weed.

"It’s not going to be a silver bullet and I don’t think anything is.  But I think it’s going to have a dramatic impact," said Dr. Neil Reimer, plant pest control branch manager with the state Department of Agriculture.

Fireweed originates from Madagascar and it's believed to have arrived in Hawaii in the 1980s through imported mulch.

It can kill cattle and horses and has infected about 850,000 acres, mostly on Maui and the Big Island.

Parker Ranch's livestock operations manager said it's a remedy that's long overdue.

"We have about 130,000 acres and all of our more productive areas are seriously affected, in some areas, a 40 percent reduction," said Keoki Wood, Parker Ranch's livestock operations manager.

But better late than never, is the feeling from ranchers now.