In tests of response of adult apple blotch leafminers,Phyllonorycter crataegella(Clemens), to sticky-coated rectangles of various hues and shades hung in apple trees, captures were consistently greater (though not always significantly so) on red rectangles than on green, orange, blue, yellow, black, gray, white, clear Plexiglas, or aluminum foil-covered rectangles. Captures were greater on horizontal red rectangles (sticky surface up) positioned at 0.5 m height and within 0.5 m of the tree trunk than on red rectangles of other orientations or positions. Such rectangles offer considerable promise for monitoring adult populations of this important apple pest.