CASPER, Wyo. (AP) — Cheyenne is spraying trees to prevent them from being infested in with mountain pine beetles.

The city is spending tens of thousands of dollars to spray all of its 4,000 pine trees. The city's urban forestry director, Lisa Olson, told the Associated Press that the department has cut back on other programs to treat the trees with a spray that kills the beetles.

Les Koch of the Wyoming State Forestry Division says beetles can be carried from one part of the state to another in firewood.