The number of Colorado lodgepole pines killed by bark beetles jumped nearly fivefold in 2006 as the explosive, decadelong bug epidemic continues to gain steam. About 4.8 million lodgepoles were killed this year, up from roughly 1 million trees last year, according to Bob Cain, an entomologist with the U.S. Forest Service in Golden. The lodgepole acreage under attack by mountain pine beetles jumped about 50 percent this year to 644,840 acres, up from 430,526 acres last year. The new numbers, which are considered preliminary, come from aerial tree-damage surveys conducted this summer. "We had a significant increase in both...