The functional response ofOrius insidiosus(Say) to densities of the European red mite,Panonychus ulmi(Koch), was studied at 18.3, 23.9, 29.4, and 35.0°C with prey densities of 5–80 mites per cage. Mite consumption was recorded during five, 3-h intervals during the day.O. insidiosusexhibited a functional response and increasing temperatures resulted in increased feeding at most prey densities. Data provided a good fit to both type-2 and type-3 functional response models.