Light-brown apple moth (Epiphyas postvittana) has developed a low level of resis~ce to azinphos-methyl in two small areas of a major horticultural district in New Zealand. It is not known whether n!sistant individuals form isolated populations or are a part of a much largerpopulation. Hence, it is uncertain whether this resistance has the potential to develop and .spre~d. .Models representing the range of possIble sltuauons are described and management options assessed by deducing the consequence they would have in each of the possible situations. It is conclu~ed th~t. the continued use of organophosphate msecucldes incurs the risk of a deVelopment and spread of resistance. The best altema.tive is to use pyrethroids in the affected areas but such an option is not without its own costs.