Spoiled tentiform leafminer, Phyllonorycter blancardella (F.), moths collected from Western New York commercial apple orchards were highly resistant to azinphosmethyl and carbaryl but susceptible to demeton, endosulfan, methomyl, and oxamyl. Apanteles ornigis Weed, a parasite of the leaf miner, was highly susceptible 10 all of the aforementioned insecticides. The susceptibility of leaf miner larval populations to systemic organo phosphates was low, and about twice the recommended field rates were required to obtain control. Control is recommended by using the systemic carbamates methomyl or oxamyl when larval populations exceed action threshold levels of one mine per leaf during the first brood or low mines per leaf during the second brood.