If the mudbugs are a problem they should just start boiling and eating them. http://m.huffpost.com/us/entry/freshwater-crayfish-the-f_b_9812908.html
While it's true that they'll eat rice seedlings, farmer's who crawfish do so behind a rice crop rotation. There's a way to do it that it doesn't interfere. Crawfish burrow when water warms up. That's when their shells get red, and hard. Rice fields are planted (if not "drilled" aka "dry-planted) then flooded, then water let go for seed germ to attach to mother earth. Won't be crawfish hanging around in a couple of inch flood then drain. As for making dams' banks collapse, hmm. I know the levees in rice fields are like brooders. We used a "Terrace plow" and had levees with at least 9 foot bases. They can burrow up to several feet deep.
