The worms at fish & tackle shops you need to be careful about. One thing to look for when buying these worms is making sure they don't have any additives - injected or soaked in (Scents, dyes, flavorings, nitrogen). I get mine in a tub that just says "Bait Connection 25 count large night crawlers" in the sporting goods section of Walmart. They're sold for people who use them as catfish bait.