Insecticides commonly used for STLM control (methomyl, oxamyl, and pyrethroids such as esfenvalerate) are highly toxic to predatory mites. Because they greatly reduce mite predator numbers, applications of these insecticides to control STLM often lead to outbreaks of European red mite (Panonychus ulmi) (4,7). In a typical year, however, leafminer populations in most New York orchards do not reach densities high enough to justify insecticidal control. A sampling program that would enable growers to determine the need for controlling STLM would reduce pest control costs by eliminating the need for preventive treatments, and minimizing disruption of naturally occurring biological control of European red mite. This report describes such a sampling program for second generation STLM.