They can be used for bait or supper. My family has been using this method forever and has caught more crawdads than you would believe. Needed items: 2 liter soda bottle knife stapler 20 feet of twine bait First off cut the 2 liter in half with the knife leaving the top part about 3 inches short than the bottom half. Next put the top half neck down into the bottom half and staple the cut tops together. The neck of the bottle will be inside the bottom and have no other exits for anything that goes in through the neck. next take the stapler and staple the twine several time to the stiff bottom of the bottle. The last step is to bait your trap. I prefer dead fish, but dog food works great too. Now that the trap is ready find a stream or pond with crawdads in it and toss the trap in the water, and tie the end of the twine to a nearby object. The crawdads will crawl in the trap for the bait and wont be able to find the way out. Check the trap in the morning and evening, and rebait as needed.