Department of Agriculture

HONOLULU – Hawaii ranchers are hopeful that a small beige-colored moth will be able to control the fireweed, an invasive plant that is toxic to livestock and has caused havoc on the state’s prime pasturelands. For more than 13 years, entomologists and researchers at the Hawaii Department of Agriculture (HDOA) have literally searched the world for a natural enemy of the weed that would be safe to release in Hawaii. The most promising turned out to be an insect called Secusio extensa (Arctiidae), the Madagascan Fireweed Moth, the larvae of which voraciously eats the leaves of fireweed.

It is believed that the weed came to the islands in hydromulch material imported from Australia where it is a serious pest. HDOA entomologists on Oahu have begun stepping up production of the moth after receiving the long-awaited approval from the U.S. Department of Agriculture (USDA), which came on Dec. 6, 2012. The state approved the release of the moth in 2010, but also required approval of a federal permit.  The first release of the biocontrol insects is slated for early 2013, depending on the rearing of the insects in the laboratory.

“Years of extensive research have been conducted on this biocontrol program,” said Russell S. Kokubun, chairperson of the Hawaii Board of Agriculture.  “Control of this weed is one of the more important issues to Hawaii ranchers, and we are hopeful that it can be controlled by this natural process.”

“Fireweed has become an even more aggressive pest during this extended period of drought,” said 
Dr. Tim Richards, president of Kahua Ranch on Hawaii Island. “So it’s even more critical to our industry’s sustainability that an effective control prevents additional loss of productive pasturelands.”