OK here is the skinny on worms.Crawlers or canadian crawlers are "night crawlers" the largest of the worms.Next in size are the dillies which are smaller nightcrawlers,then you have what we up here in NE call worms or trout worms which are commonly called red wigglers in the south but do not have the red color that the southern variety has.If you are fishing for trout or panfish variety of fish,crappie,bluegill.pumpkinseed,ect. than use the trout worms.For everthing else I use dillies.For trolling for salmon or catfish(hornpout) I use crawlers.I hope this helps.Bubba