LINCOLN, Neb. (AP) — State officials say an insect that’s killed millions of ash trees in the U.S. has been found further west into Nebraska.

The Nebraska Department of Agriculture says the emerald ash borer has been found in Lincoln and Fremont. The insect was found in a baited trap in Lincoln set up by the U.S. Department of Agriculture as part of a national survey.

In Fremont, an ash tree with signs indicating an infestation was also recently discovered.

Infected trees usually lose leaves at the top of the canopy and the die-off spreads downward. The trees usually die within four years.

The insects are native to Asia and were first reported in the U.S. in Michigan in 2002. They were first detected in Nebraska in Omaha and Greenwood in June 2016.