Resistance to pyrethroid insecticides has been reported from Thailand, Central America and Australia in Spodoptera and Heliothis species. The diamondback moth Plutella xylostella, from Taiwan shows very high resistance to all pyrethroids. The resistance to pyrethroids in H. armigera in Thailand is extremely serious. The outbreak of resistance of H. armigera in Australia is being combated by an agricultural resistance management scheme that is unique in the world.