A tiny Asian fly that feeds on pasture grasses showed up in Georgia two years ago, the first time the species was documented in the Western Hemisphere. It's now moved to Florida and possibly other Southern states.
Atherigona reversura calls Japan, Indonesia, India and even Hawaii home. It was confirmed for the first time on the U.S. mainland in a bermudagrass pasture in Pierce County, Ga., near Savannah in the fall of 2010, said Will Hudson, an entomologist with the University of Georgia Cooperative Extension, at the 5th annual Southeast Hay Convention.
A puzzling presence
The mystery is how this Asian native suddenly emerged in the southeastern U.S. The U.S. doesn't import much live grass from other countries. "In fact, the flow is the other way. We send sprigs of our grass all over the world for golf courses and things like that. It's a real puzzle how it got here," said Hudson
The fly has been found in Mexico and is suspected in California and New Jersey, Hudson said. "It is a surprise to find them that widespread when no one had any idea they were here. That is the unusual thing."
It is hitting some north Florida counties pretty hard, such as Madison, Alachua, Gadsden and Bradford counties, where as much as 20 percent of the late-summer hay harvest has been damaged, said Tim Wilson, a University of Florida Extension agent in Bradford County.
"The reality of the permanent presence of this insect pest to bermudagrass may cause us to increase pyrethroid applications to hay fields or cut and harvest bermudagrass when fly populations are high," said Ann Blount, University of Florida forage breeder studying the new invasive pest in that state.
Dines on the tips
"The adult fly lays eggs, and the maggot bores down the stalk of grass. When it completes its development, it pupates and emerges as a fly," Hudson said.
The fly only destroys the top two leaves of a plant. Bermudagrass is an important crop grown from North Carolina to Texas as a pasture grass or for hay. This type of grass seems to be the most damaged by the fly, particularly the finer textured and most widely planted bermudagrass varieties Coastal and Alicia.
"A badly infested pasture or hayfield, if you look at it, looks like a frost came along and just nipped the tips, just the very tips. The green underneath is fine," he said.
Mowing or cattle grazing are effective ways to control the fly. "The cattle just get a little extra protein when they eat the maggots," said Hudson. "But for the hay producer, this could mean missing out on a late-season, or that last cutting of the year."
Farmers in the Southeast, particularly the Deep South, are asked to contact their area Extension agent if they suspect damage from the fly this year. Researchers want to get a handle on how big an impact this tiny fly could have.