Female Panagrellus silusiae produce a substance that attracts males. Males do not produce attractant, nor is there homosexual attraction. The attractant is water borne and forms a gradient in agar. The attractant is first produced by females during the fourth juvenile stage and males first respond to the attractant during the fourth juvenile stage. Female Cephalobus persegnis also produce an attractant, but the attractants of each species only attract males of that species.