The Minnesota Department of Agriculture is preparing to hang thousands of traps across Minnesota in the hunt for emerald ash borer. State workers begin the job this 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. Officials say it’s important for the public to leave the traps alone because they’re 1 of the few options available for detecting the beetles. Traps will not be placed in the four counties currently under quarantine for emerald ash borers: Houston, Winona, Hennepin and Ramsey, but will be put up throughout the KNUJ listening area.