BILLINGS, Mont. -

A U.S. Forest Service official says mountain pine beetle activity is declining in Montana.

Gregg DeNitto of the Forest Service's Health Protection office in Missoula says that the peak of the epidemic may have passed.

The finding is the result of aerial surveys last year and analyzed in the 2011 Montana Forest Insect and Disease Conditions report prepared by the Forest Service and state Department of Natural Resources and Conservation.

But the report also found emerging problems with western spruce budworm and pine butterfly.

The report covers about 20.5 million forested acres in Montana, including federal, state and private lands.

The survey found beetle-killed trees on more than a million acres, but that's down from 2 million in 2010 and 3.6 million in 2009.