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Jul 5, 2014 9:32 PM by JANET McCONNAUGHEY

Crawfish castles in lawns can be irritating

NEW ORLEANS (AP) - The little hollow mudball towers called crawfish castles are fine in the swamp but not so great in your yard.

"They're hard on lawnmowers and mower blades and that kind of thing," said Lee Townsend, an extension entomologist at the University of Kentucky in Lexington. If the soil holds much clay, "they bake and harden like a brick," he said.

Greg Lutz, a crawfish specialist at the LSU AgCenter, says he's been getting calls from around Louisiana from people who want to get crawfish out of their yards.

He usually gets about 30 to 50 such calls a year and this year has run about average, he said in an email.

Many are in early summer when mothers have carried their young to the nearest ditch, stream or lake, then returned to their burrows to clean out and enlarge them. Young crawfish may be digging their first burrows, Lutz said in a news release.

There are a couple of big problems clearing out crawfish. For one, Lutz said, the U.S. Environmental Protection Agency hasn't approved any pesticides for crawfish.

States can get the occasional exception. For instance, in 2010, Wisconsin got permission to use a pesticide to control red swamp crayfish at three specific spots, including the stormwater catch basin and burrows next to the Germantown Police Department in Washington County.

Putting pesticides into the burrows can contaminate groundwater, Lutz said.

"Using pesticides in burrows is not only a bad idea, it's also illegal. And putting bleach down in the burrow is often ineffective," Lutz said.

A fact sheet by Townsend, recommending two possible treatments, has been cited in a number of Internet discussions of lawn crawfish.

That fact sheet was created in the 1960s and has long since been removed from the extension service website as outdated, Townsend said in a telephone interview.

There aren't a lot of choices, he said.

Another problem is that the crawfish might be protected.

Of more than 350 crawfish species in the United States, about 65 are endangered, threatened, or listed as species of special concern by the states in which they live, and 48 percent are in need of protection, according to Virginia Cooperative Extension at Virginia Tech.

Although Louisiana raises and catches more than 50,000 tons of crawfish a year to eat, the 39 species found in the state also include more than a dozen considered rare or even critically imperiled by the state Department of Wildlife and Fisheries.

If there are only a few holes, they can be filled with water to flush out the inhabitants, said Robert Romaire, another LSU AgCenter crawfish expert.

For common species, Lutz said, one way to kill them is pouring about a tablespoonful of lye into each hole. Lye turns into harmless byproducts as it migrates into the soil, he said, but is caustic: the user must protect skin and eyes.

He emphasized in an email that he can speak only for Louisiana because rules vary widely from state to state.

The North Carolina Extension Service suggests raking the mounds smooth from time to time, creating drainage to leave surface soil less soggy, or just appreciating crawfish as one would an "interesting bird or turtle."

Crawfish appreciation is the tack taken by writer and artist Ursula Vernon of Pittsboro, North Carolina, after a burrow she thought might house some sort of rodent turned out to be home to a crustacean.

"Once I finished running around like a chicken with its head cut off, I thought it was kind of cool," she said.

She doesn't know what kind of crawfish it is, or how it made it into her yard: "The nearest lake or significant drainage ditch is miles away. So he had to walk a long way."

Generations of Louisiana children have tied a bit of meat to a string, lowered it down into a crawfish hole and pulled it up slowly to see the inhabitant.

"I tried that," Vernon said. "I got him a little ways out and he took the meat away from me. It was very embarrassing. You hate to be outsmarted by a 4-inch long crawfish."

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