Evaluation of color traps for Lygus spp.: Design, placement, height, time of day, and non-target effects

Lygus hesperus and L. lineolaris are two of the most economically important plant bugs in North America. Here we present results from field trials that evaluated effective trap characteristics for maximizing Lygus spp. and other herbivorous insects capture, while minimizing beneficial insect capture. The response of lygus bugs, several other key herbivore species and predators to hue (white, clear, black, yellow, orange, blue, purple, green and red) and value (black, white and two neutral grays) was examined in alfalfa over three seasons using traps coated with Pestick adhesive. Lygus spp. exhibited a broad response to trap hue, but showed no response to trap value or intensity. Additionally, we showed that time of day, trap height, and trap placement influenced the number of Lygus spp. captured. More Lygus spp. were trapped from late afternoon to dusk compared to all other times of the day, and more males than females were captured on sticky traps even though the sexes were at parity in field sweep net samples. In the alfalfa setting, male lygus were more likely to be captured on traps placed 20 cm above the ground; traps placed 50 and 100 cm above the ground caught similar numbers of males and females. The highest number of plant bugs was captured when traps were placed in a cleared area between two alfalfa fields; lower numbers were captured on traps at the edge and in the center of the field. All other herbivores exhibited distinct preferences to trap hue and in some cases, trap value or intensity. Predators were rarely trapped, but did exhibit preferences to trap color (i.e., hue and value) characteristics. The potential of using sticky traps with specific hue and value characteristics to effectively monitor Lygus spp. is discussed.