Caven's Beaver Castor (ground) Lure Ingredients Large 4 Ounce Jar Trapping Supplies Ground and preserved. One of the oldest animal attractors known to man. Attractive to all furbearers. Heavy paste second to none. Use to create a lure, use straight at a castor mound set, or smear on a post for a post set. Very versatile. The castors are dried and then turned into a paste using glycerine.