The effect of different trap colors and lures on capturing Chrysobothris mali (Coleoptera: Buprestidae) in California walnuts

The Pacific flatheaded borer, Chrysobothris mali, has emerged as an increasingly significant pest in walnut orchards in California in recent years. Host abundance and changing environmental factors, such as drought, contributed to the outbreak of this pest in 2018 in the Central Valley of California. Understanding the seasonal occurrence of this pest enables timely and effective management.

In this study, we evaluated various trap colors and lures for monitoring adult beetles in walnut orchards throughout the season. Triangular traps in six different colors—purple, yellow, red, grey, black, and green—were installed at the beginning of May. In a separate trial, purple triangular traps were paired with two different lures, and a control group with no lure was included. From early May to September, traps were checked weekly, and the number of captured adult beetles was recorded. Red and yellow traps attracted significantly more adult beetles compared to the other colors.