GULF BREEZE, Fla. — State agriculture inspector Laura Ooms knew at first glance something was seriously wrong with a couple of prickly pear cactus plants in the garden section of a Wal-Mart store in this Pensacola suburb.
"They were quite ridden with worm holes," Ooms recalled. "It wasn't one little worm hole. There were several holes in them. They were oozing."
She cut one cactus open and inside saw red-orange caterpillars with black spots, the larvae of Cactoblastis cactorum, commonly known as the cactus moth.
Native to South America, the gray-brown moth is a minor pest in the Southeast, dining on ornamentals and a few native species.
But it could cause economic and environmental havoc in the American Southwest and in Mexico, which is where it is headed. And infestations discovered across the Florida Panhandle show that it is gaining speed.
The invasion began 14 years ago in the Florida Keys. Since then, the moth has eaten its way up the eastern seaboard to Charleston, S.C., and along the Gulf Coast to within four miles of the Florida-Alabama state line, said Ken Bloem, a U.S. Department of Agriculture scientist in Tallahassee.
The moth's rapid advance is particularly worrisome in Mexico, where prickly pear cactus is a cultural icon — its image is on the Mexican flag and coins — and an economic mainstay.
"We eat cacti, we produce pharmaceuticals with cacti, we export cacti," said Jorge Soberon, executive secretary of CONABIO, the Mexican National Commission on Biodiversity. "It is used as cattle fodder mainly during the dry years."
Cactus is a $50 million to $100 million a year industry in Mexico, which has 56 prickly pear species. Many people also rely on it for subsistence, Soberon said. Prickly pear fruit can be made into jam and syrup while the plant itself is commonly boiled or pickled.
In the Southwest, prickly pear is an important horticultural plant. Arizona nurseries alone maintain inventories with a retail value of close to $10 million, according to a survey by horticulturist Mary Irish.
Environmentally, cacti prevent erosion and are a habitat and food source for animals and birds.
"The Mexican government has already issued alerts in the (Mexican) states that thing will probably invade," Soberon said. "I don't think your Department of Agriculture is really interested in the problem, and understandably because cacti are not a major crop in the U.S."
Bloem, co-director of the Center for Biological Control set up by the Department of Agriculture and Florida A&M University, defended the U.S. response to the cactus moth.
"I think the U.S. is taking it fairly seriously," Bloem said, but he acknowledged: "At this point in time, nothing is actively being done to stop them."
The cactus moth is a proven killer. Prickly pear planted in Australia as a natural cattle fence grew out of control and took over 16 million acres, but it was virtually wiped out after the moth was imported in 1925.
The female lays sticks of eggs that look like cactus spikes. When they hatch, the caterpillars bore holes and begin eating the cactus from the inside out.
The moth also has been used as a biological control in Hawaii, India, South Africa and the Caribbean, unintentionally spreading from there to the Florida Keys in 1989.
In the Keys, the moth quickly killed one of only a dozen adult semaphore cactus plants then known to exist, all in a Nature Conservancy refuge. Cages were put around surviving plants to keep the moths out.
Fearing the screening would caused more harm than good if battered by a storm, it was removed as Hurricane Georges took aim at the Keys in 1989, said Doria Gordon, a senior scientist with the Nature Conservancy in Gainesville.
The organization now uses volunteers to inspect the semaphores, including several hundred plants later discovered at a second site. The volunteers pluck egg sticks and remove infested pads without killing the cacti.
Mexico plans a similar low-tech approach if the moths get there as expected, Soberon said.