Resistance to synthetic pyrethroid (SP) insecticides in the tobacco budworm (TBW), Heliothis vireacens (F.), has become a major concern to cotton producers. We describe here a technique that will allow for rapid determination of SP resistance in TRW larvae. The technique involves exposing field-collected larvae to cypermethrin residues in glass vials and determining % survival (resistance) 24 hours later. In conjunction with adult monitoring procedures developed earlier, the technique should enable cotton producers to make informed decisions concerning appropriate control measures for the TBW.