Brian, no kidding this time, I did some searching and finally found some usefull information. Here's one quote from Texas A and M.
QUESTION: I am looking for information on how to get rid of crawfish in my yard and garden. If you know anyone who can help, please advise.
Louisiana is the only one brave enough to publish a recommendation for crawfish control, since there are no labeled products on the market. They used to recommend Sevin 50% WP mixed at a rate of 8 Tbsp/gallon with 1 oz of mixture applied per hole. This Sevin formulation, however, is not available to consumers. Permethrin (Spectracide Bug Stop) could be applied to the mound as it would be used on a fire ant mound. A few ounces of mixture is probably all that is needed, compared to the 1-2 gallons per mound recommended for ant control.
There are currently no pesticides registered for control of crawdad mounds. One problem with controlling crawdads is potential contamination of nearby streams or ponds.
One insecticide is reported to work well on crawdads. Permethrin (Spectracide Bug Stop) could be applied to the mound as it would be used on a fire ant mound. A few ounces of the mixture is probably all that is needed, compared to the 1-2 gallons per mound recommended for ant control. I would not recommend treating crawdad mounds that are closer than 10-15 feet of a stream or pond for fear of contaminating the water.
Also check out these two links for more info, check out Bugspray.com and University Of Kentucky. Or as a last resort call the Beverly Hillbillies, Granny or Jethro would be more than happy to smoke them for you (LOL)! Hope this helps! Wick