ST. PAUL — The Minnesota Department of Agriculture is preparing to hang thousands of traps across Minnesota in the hunt for emerald ash borer. State workers will begin the job in the coming week.

Around 6,500 purple traps will be placed throughout the state, about 2,000 more than last year, to detect new infestations of the destructive tree pests. The traps are three-paneled purple prisms placed in ash trees. A lure inside the trap smells like a stressed ash tree to the beetle.

Plant Protection Division Director Geir Friisoe said it’s important for the public to leave the traps alone because they’re one of the few options available for detecting the beetles.

Traps will not be placed in the four counties currently under quarantine for EAB: Houston, Winona, Hennepin and Ramsey.