DES MOINES, Iowa (AP) — State agricultural officials say an insect that’s killed millions of ash trees has been found in three more Iowa counties. Officials said in a news release Wednesday that the emerald ash borer has been confirmed in Crawford, Delaware and Page counties. That brings Iowa’s total to 64 counties.

People are urged to report any suspected infestation. Mike Kintner with the Iowa Department of Agriculture and Land Stewardship says tracking the whereabouts of emerald ash borers across the state helps in formulating treatment recommendations. 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 bugs are native to Asia and were first reported in the U.S. in Michigan in 2002 and in Iowa in 2010.