This is evidence of pine-beetle infestation with which parts of Colorado and Wyoming have been contending the last few years. The US Forest Service and private landowners have been removing the afflicted trees as time and budget permit. So you may also encounter logging activity, at least in North Park.
On a brighter note, July is wildflower season in the Colorado High Country.
You may see wildflowers including St. John's Wort, Foxglove, Columbine (Colorado state flower), and dozens of other varieties of alpine and subalpine blooms.