"TRAVERSE CITY, Mich. — Marauding insects have become a leading threat to the nation’s forests over the past decade, a problem made worse by drought and a warming climate, a federal report says.
Bark beetles, engraver beetles and gypsy moths are the primary culprits behind a threefold increase in forestland mortality caused by insect attacks between 2003 and 2007, according to a U.S. Forest Service report obtained Wednesday by The Associated Press. The volume of forests in the lower 48 states killed by bugs totaled 37 million acres during the period, up from 12 million during the previous five years. Millions of additional acres have perished since.
When defoliated trees are added to those killed outright, the acreage significantly damaged by insects since 2003 totals about 50 million — 8 percent of forest area in the lower 48 states, the report says. The victims range from Rocky Mountain pine forests hammered by bark beetles to ash stands in Northeastern and Upper Midwestern states, where authorities have struggled to contain an emerald ash borer invasion."