Montana Tries Using Color to Trap Insects

Red, green appear to attract more sweetpotato weevils.

Published on: Jan 30, 2014

Red and green traps attract more sweet potato weevils than other colors, and a Montana State University researcher who made the discovery wants to know if other  pests react to colors.

Gandi V.P. Reddy, entomologist and superintendent of MSU's Western Triangle Agricultural Research Center in Conrad, says the lessons he learned in Guam and published in the "Annals of the Entomology Society of America," will be tested on some of the major pests that destroy Montana's wheat, barley and canola.

Those insects include adult click beetles (wireworms), flea beetles and wheat stem sawfly. The sawfly is the most destructive wheat pest in the state, with wireworms a close second. Flea beetles are a major pest in canola, an increasingly interesting crop to farmers in the West.

Montana Tries Using Color to Trap Insects
Montana Tries Using Color to Trap Insects

Reddy discovered the relationship between colors and insect trap effectiveness while developing a trapping system for sweet potato weevils. He used a  variety of traps that used pheromones to attract insects.

Previously, the sweet potato weevil was shown to prefer red traps over gray, green, brown, blue white, black of yellow. Light red was more attractive than other shades, so Reddy launched a new study.

But when the pest in indoors (sweet potatoes in storage are also menaced by the pest) the bug seemed to come to green traps more often, says Reddy, who says the information is helpful in management of pests.

With or without pheromones, green traps catch "significantly" more adult sweet potato weevils than any other color, he concludes.

What remains a secret is why color makes a difference, a question Reddy plans to pursue in future probes. In the meantime, he has already started testing different colored traps in Montana fields.

There is an "urgent need" to develop eco-friendly control methods for weevils, he notes. "Although some control methods are effective, toxic pesticide applications are detrimental and damaging our environment," he adds.