Crawfish In Your Lawn? Hope You're OK With That

Apr 25, 2017

Call them crayfish, crawfish, crawdads, or mudbugs, 'tis indeed the season for crawfish ---- and the clay chimneys they leave for a calling card ---- in yards and ditches all over Northeast Texas.

If there’s a love ‘em or hate ‘em animal living deep in the soil beneath your otherwise manicured lawn, it is the crawfish. Foodies and animal lovers love them (for admittedly different reasons); people mowing their yards hate the mounds and holes they leave everywhere.

So let’s say you hate ‘em. Let’s say you want to rid them from your property. What exactly can you do about it? Well, the short answer is, you can get used to them.

“It’s almost like mosquitoes,” says Dr. Rusty Gaude, a crawfish expert at Louisiana State University. “If your habitat is acceptable to them, then you will eventually have them.”

And, like mosquitoes, they’re not easy to get rid of because they’re ubiquitous, they move fast, and they’re patient.

Gaude is aware that some people might consider using a pesticide to get rid of the crawfish on their property. Don’t. For one thing, there are no pesticides approved for use on crawfish. Those little mudbugs are highly resistant to poisons and they live near the water line under the soil anyway. That means that even if there were a poison for them, you’d have to use supervillain-level amounts of pesticide to reach them. And that would contaminate the groundwater.

And, Gaude says, even if you killed off all the crawfish on your property, the next rainfall would just bring them skittering over from your neighbor’s yard.

“Their big game is waiting,” he says. “They burrow down into these chambers and basically wait for some sort of water event, be that rain, a flood, dishwasher backs up, whatever. And then they will make a very quick and definitive move to get out and start completing their life cycle.”

For the record, there is one environmentally safe substance that seems to work well against crawfish ‒‒ potassium hydrochloride, a caustic salt known more commonly as lye. But just in case you thought there wasn’t a catch, lye is a key ingredient in making crystal meth.

Technically, it is entirely legal to buy lye, even in bulk. Special Agent Elaine Cesare at the Drug Enforcement Administration office in Dallas says drugmakers use red devil lye --- the kind used to make soap and homemade cleaning agents ---- to mellow out the GHB in meth. And yes, GHB is the charmingly monikered date rape drug.

Regardless, lye is not regulated, meaning it’s not legally considered a precursor chemical. So you can buy all you want – if you can find it. Turns out, asking a store clerk at a big box home center for a 50-pound canister of lye is a sure way to elicit some stunningly interesting looks.

Beyond the chemicals and meth recipes lie drastic measures like draining the ground. Which would, also for the record, would succeed at killing crawfish. But that’s a whole other problem.

“You’re not going to effectively get rid of all the water in the ditch without effectively getting rid of all the water in your yard that’s underground that you can’t see,” says Dr. Zachary Loughman, a crawfish researcher at West Liberty University in West Virginia. “What you’re doing is, you’re making your yard a desert.”

About a decade ago he did a survey project on crawfish around eastern Texas. And, like Rusty Gaude, Loughman says there really is not a good way to get rid of them. His advice?

“Learn to live with them,” he says.

So instead of than being angry at these hardy ditch dwellers for ruining your mower blades and uglying up your yard, perhaps a change of attitude is the better bet. While Loughman sympathizes with lawn enthusiasts everywhere, he says crawfish in the ground are actually quite beneficial to the environment.  

“Crayfish are really, really important to ecosystem functioning in that part of the world you’re in,” he says. “The amount of soil that they’re moving is insane. There was one study that found that there was over 40 tons of soil being moved in these forests by these crayfish over the course of a year, and if you lost that function from the ecosystem, all the plants that live there would probably die.”

This is all well and good for forests and ditches and yards. But when crawfish get into streams or river beds, their aggressive, invasive nature can completely upend an established ecosystem ---- like they’ve done in Southern California. Dr. Lee Kats is a professor of biology at Pepperdine University in Santa Monica. His current research is on the causes of amphibian decline in Southern California, and his shortlist of suspects begins and ends with crawfish.

“Ecologically, they’re nothing but negative,” Kats says. “They’ve already driven some of our local amphibian species to extinction from some of our local habitats.”

Kats says that “kindhearted” fishermen in the 1960s, using crawfish as live bait, released leftovers into the Santa Monica waterways, not realizing what ecological damage they were about to unleash.

“Native amphibians were in all of my local streams in the 1970s,” he says. “But by the 1980s they were wiped out and our data show that it’s probably the crayfish that wiped them out in that 10-year period.”

Moreover, Kats says, crawfish insatiably feed on the eggs of amphibians and invertebrates --- critters that eat mosquitoes. But they themselves don’t eat mosquito eggs because they’re too small.

So the implications are obvious for Northeast Texas, where mosquitoes are plentiful and known carriers of West Nile virus. But therein lies a pressing question: Do those crawfish in the yards and ditches pose a threat to freshwater aquatic life in this region, if they get into the waterways?

Well… maybe. Dr. Tim Patton, a biologist at Southern Oklahoma State University says Northeast Texas and Southeastern Oklahoma lie just north of the native range for red swamp crawfish ---- the type in most yards in the region. And also the type gumbo enthusiasts prize most. The trouble is, it’s hard to know what, if any, negative effects crawfish might have by being almost-native ---- because, as it turns out, no one is looking into the matter.