Color, pattern, and background contrast affect attraction of Euxesta eluta and Chaetopsis massyla (Diptera: Ulidiidae).

Euxesta eluta Loew and Chaetopsis massyla Walker (Diptera: Ulidiidae) are primary pests of sweet corn in Florida. Attraction of adult flies to various visual stimuli was evaluated in the laboratory to provide insight into the potential development of enhanced trapping strategies. In assays evaluating different colored sticky traps, more E. eluta were collected on light blue, mid blue, lime green, and orange yellow traps, whereas attraction of C. massyla was greater to lime green and fluorescent green traps. In a comparison of yellow 3-dimensional shapes, more E. eluta were collected on yellow cylinders than on spheres or cubes; however, more C. massyla were collected on cylinders than on cubes or spheres. When colored traps were placed against a white background, more E. eluta were collected on lime green compared with yellow, blue, and orange traps; however, when placed against a black background, attraction to the lime green trap was reduced. Against the white background attraction of C. massyla, was strongest to yellow, then lime green and orange traps, followed by blue, but with a black background, differences between traps collections were reduced. The addition of ultraviolet (UV) reflectance to yellow increased the attraction of E. eluta, but C. massyla were more attracted to yellows without UV reflection or fluorescence. Black patterns on yellow traps affected attraction, with E. eluta more attracted to wide stripes, a large square, or many small squares, whereas C. massyla was more strongly attracted to stripes. Utilization of these visual attributes could be useful in improving surveillance for these species.