Australian Moth May Subdue Invasive Fern

A tiny moth from Australia may become the first insect used in the United States to fight Old World climbing fern–an invasive weed that threatens Florida’s Everglades and other native ecosystems.

Known as Lygodium microphyllum, the fern forms walls of light-green vegetation when it makes its way up tree trunks and into the canopy. It also forms tough, spongy mats that smother low-growing plants.

The moth, Cataclysta camptozonale, measures only a half-inch from wingtip to wingtip. It is bright-white with a few black and brown spots and stripes on its wings.

Scientists at the ARS Australian Biological Control Laboratory at Indooroopilly, Australia--near Brisbane--collected the fern-fighting moth and tested it with 15 different kinds of ferns. Experiments led by laboratory director John A. Goolsby indicated that the moth’s slender, wormlike larvae will feed on--in addition to climbing fern--a related weed called L. japonicum and a native North American fern called L. palmatum. Goolsby expects follow-up tests at Indooroopilly to show that the subtropical moth could not survive the cold temperatures of the eastern United States, where L. palmatum ferns grow.

Goolsby and colleagues with Australia's Commonwealth Scientific and Industrial Research Organization have sent more than 250 C. camptozonale moths to Gainesville, Fla. There, the insects will undergo testing by Gary R. Buckingham of the ARS Invasive Plant Research Laboratory, and by University of Florida co-researchers. If those studies and additional experiments in Australia show that the moth won’t harm native or crop plants, the researchers may seek federal and state permission to turn the helpful insect loose at climbing-fern-infested sites in Florida.

Aerial surveys by the South Florida Water Management District indicate that the fern spread from an estimated 39,000 acres in 1997 to more than 100,000 acres in 1999.

Scientific contact: John A. Goolsby, ARS Australian Biological Control Laboratory, Indooroopilly, Queensland, Australia, phone 617 3214 2821, john.goolsby@brs.ento.csiro.au.