Crawfish Shells Harden Up… as Summer Heats Up!

Louisiana crawfish with hard shells

By Patrick D. Bonin


Branch, LA – Ever hear that old expression about needing to have “thick skin?”

Crawfish in ponds across south Louisiana seem to take it to heart every summer about this time, as their shells start to harden while the heat cranks up.

You might even notice some mudbugs are a bit tougher to peel this late in the season… but do you know why?

Mark Shirley, aquaculture specialist at the LSU AgCenter, said several factors influence the hardening of a crawfish’s shell, chief among them age.

“Immature crawfish go through a series of molts before finally becoming a mature animal,” Shirley said. “Once they reach sexual maturity later in the season, that shell will stay with them for several months before they molt again.

“It typically takes 12-15 molts for a crawfish to reach maturity, and sometimes they molt as often as every two to three weeks early on,” he said. “So at the start of the season, there’s a quick turnover with the shells: now there isn’t. That allows for a thicker, heavier shell.”

Shirley said most mature crawfish now won’t molt again until next fall when the ponds are flooded and they emerge from underground. In the meantime, their tough exteriors serve them well as they prepare to tunnel down to escape the summer heat.

“The harder shell enables them to dig a burrow better and easier, and gives them a better chance of surviving underground,” he said.  “They’re sitting down there for all of July, August and September. Sometime in October they’ll typically emerge from their burrow not having molted since late spring. “

These mudbugs that survive a harvest season and are used to seed next year’s ponds are typically the really large crawfish you’ll notice in future boils.

“If you find a male with really big claws in December or January, he’s a mature crawfish who’s probably gone through a season,” Shirley said. “When they come out of their burrows next fall, they have to eat a lot for several weeks and they’ll finally molt again to get rid of that hard shell. They’ll get a ‘young crawfish’ look again, but they’re actually an older crawfish in a brand new greener, lighter-colored shell.”

So while thicker, harder shells might signal the “beginning of the end” of this season, as least we know Mother Nature is already at work preparing the mudbugs so they can make it through summer and emerge in the fall… with another brand new crop of live Louisiana crawfish for 2014!