The New Orleans skyline is plainly visible from a Gretna neighborhood, where a canal winds past homes and a picturesque golf course. Neighbors enjoy bass fishing, but just below their feet lies an invader.  The bright pink clusters of apple snail eggs dot the canal banks, glued to the pilings of a bridge, drainage pipes, even foliage that lines the bank.

“I saw your first report, and I also went to the web site and got more information on it, and then from there, I went out and started noticing them immediately,” said Gretna resident David Schmidt.

Schmidt seldom sees the adult apple snails, because they live below the surface of the water, but after the first Eyewitness News report about the new species being found in south Louisiana waterways, he became a man with a mission, scraping the eggs into the water to kill them.

"The first pass I made out here, I knocked probably 30 pods off the pilings. Any little stick in the water, they climb up and lay their eggs on,” he said.

Louisiana Department of Wildlife & Fisheries officials report the snails are turning up in Gretna, throughout Terrytown and Belle Chasse.  They say apple snails were first spotted in Gretna in 2006. After the first Eyewitness News report, callers pinpointed two-apple snail populations to Wildlife & Fisheries experts, in Gretna and in the Houma, Thibodaux and Schriever areas.

According to Michael Massimi with the Barataria-Terrebonne National Estuary Program, the snails are tearing up the vegetation in south Louisiana, going after any fresh water plant they can get their mouths on.  Scientists have gathered some live snails to study them, and are surprised by how much they eat.

“They eat anything we've put in here. They eat giant salvinia, which is the big plant problem we're having in the northern part of the state. We've put hydrilla, coontail,” said Brac Salyers with Wildlife and Fisheries.  “Pretty much everything we've put in here, they've eaten down to nothing."

The snails even ate dead crawfish. The concern is what damage they could do in Louisiana, especially in the rice fields where crawfish are also harvested.

“In Indonesia in particular, there is massive crop damage, into the 80 percent range of the rice farms there,” Salyers explained.  “So that is our biggest concern as far as controlling populations here, we do not want to let these things get into the Intracoastal Waterway, and make it to the west part of the state."

But the other concern is whether the snails could attack vegetation in Louisiana's fragile wetlands.

“Our wetlands are already threatened so severely by land loss and salt water intrusion. I hate to see what few remaining freshwater marshes we have convert to algae dominated ponds. It's a big threat," Massimi said.

Apple snails are originally from South America. So how did they get to Louisiana?  The answer could be that they are very popular in freshwater aquariums, and the experts say chances are somebody just tossed theirs into a local waterway.  They want to make sure that doesn't keep happening.

"If you want to enjoy it in an aquarium, that's fine, but when it gets too big, either destroy it, or give it to another person with a bigger aquarium.  That's fine.  Just don't release it into the wild,” Salyers said.

Wildlife and Fisheries agents ask anyone spotting the bright pink apple snail egg clusters to use a scraper to knock them into the water. That kills them. Adult snails can be bagged up and disposed of.

The agency is collecting reports of sightings to determine where the snails have spread. You can do so by calling 225-765-2641, or e-mailing Brac Salyers at bsalyers@wlf.louisiana.gov.