INFLUENCE OF TRAP SHAPE, SIZE, AND BACKGROUND COLOR ON CAPTURES OF FRANKLINIELLA-OCCIDENTALIS (THYSANOPTERA, THRIPIDAE) IN A CUCUMBER GREENHOUSE

Capture of the western flower thrips, Frankliniella occidentalis (Perg ande), on yellow or violet traps of four different shapes when placed in front of plywood frames painted violet, blue, green, or yellow as b ackground colors was studied in a cucumber greenhouse in 1988. Among t raps with cubic, spherical, rectangular prism, or cylindrical shapes o f approximately the same surface areas, only yellow cylindrical traps in front of a violet background were significantly more attractive tha n the other shapes. Yellow or violet traps placed in front of their id entical background colors trapped fewer thrips than if placed in front of certain backgrounds providing greater contrast. Yellow traps place d in front of violet or blue backgrounds caught significantly more thr ips than traps with yellow backgrounds, which in turn captured signifi cantly more thrips than traps with green backgrounds. Violet traps wit h a yellow background caught significantly more thrips compared with v iolet traps with blue, green, or violet backgrounds. Comparing three-d imensional versus two-dimensional traps, blue cylindrical traps did no t catch significantly more thrips per square centimeter of trap area t han did flat traps of similar diameter and height. Catch of thrips on flat traps increased linearly with increase in trap area between 74 an d 300 cm(2).