Bright red or green boxes are starting to appear tied to tree branches as the Wisconsin Department of Agriculture, Trade and Consumer Protection begins a gypsy moth survey in western and southern Wisconsin.

Adult gypsy moths will soon emerge, and the special traps will provide valuable data for the department to plan future gypsy moth treatment sites.

The traps are designed to catch and monitor the invasive gypsy moths, which fly through a small opening and become stuck. Staff with the DATCP’s Gypsy Moth Slow the Spread Program began setting traps in mid-May and will set approximately 11,000 traps across 48 counties by early July.

Traps don’t control the population but tell where gypsy moths are and where they are not, said Chris Whitney, gypsy moth trapping coordinator. Traps help determine if an egg mass survey needs to be done in the fall to better evaluate the population and if an area may need an aerial treatment the following year.

The traps catch only male gypsy moths, because they can fly and the females cannot. To find each other and reproduce, the females release a pheromone for the males to detect and follow. This pheromone is undetectable to other insects and is used as a lure in the traps.

Traps will stay in place until the male moths stop flying in August.

“It’s important to leave the traps up during moth flight to get the data we need. Then, when the moth flight ends, we’ll take them down,” Whitney said.

If a trap needs to be set on private property and the owner is present, trappers ask the owner for permission. Trappers wear fluorescent vests and carry an identification card. If the owner is unavailable, trappers set the trap, and leave an information sheet and a phone number to call for more information.

Whitney said most landowners are very cooperative, but if someone wants a trap removed, they are asked to call 800-642-6684 or visit the DATCP website at http://​gypsymoth.wi.gov.