TSA can grow taller than 3 feet and equally wide. Its leaves are covered in long spikes, and its immature fruits with pale and dark green stripes resemble small watermelons. It is an aggressive propagator, and cattle will not feed on its leaves.

TSA is native to South America and was discovered in the U.S. more than 20 years ago in Glades County. It now covers more than 1 million acres in Florida and has spread to other states including Georgia, Alabama, Mississippi and Texas.

Buzz Eaves, a cattle rancher in St. Lucie County, first encountered TSA in 2000 when it began overtaking his forage grasses. After four years of aggressive campaigning against the weed using herbicides, fire and mowing, Eaves allowed IFAS researchers to release the Gratiana boliviana beetles on his ranch. Eaves said for the first two years the beetles worked slowly on the TSA and steadily increased in number.

“And then the following year, we had pretty much reached a biological balance with the plants,” Eaves said. “The TSA plants would start growing in the springtime and be followed a month or two later by the beetles. And the beetles would work on them all summer long, and by the end of the summer, those plants would be skeletonized and away we go to another year.”

Eaves said the beetles have reduced his annual spending on TSA control from as much as $25,000 to nothing.

Medal is working to gain approval from the U.S. Department of Agriculture for the north Florida release of two more TSA biological control insects. These insects are better adapted to colder climates than Gratiana boliviana, which has failed to establish north of central Florida.