Chainsaws were buzzing in Iowa’s largest city this week as the first of thousands of ash trees were cut down. Des Moines is responding to the coming invasion of the emerald ash borer.

Municipal arborist David Jahn says the plan targets more than seven-thousand trees on public streets and in parks, while about a-third of them would be saved — for now — with pesticide injections. “We would begin our removals now in December of 2013 and over a five-year period, manage to remove all of those 4,800, while the others are being saved temporarily for later removal.”

Hundreds of small trees, and large ones with structural issues, are the first to go. The emerald ash borer has been positively identified in four counties in eastern Iowa: Allamakee, Des Moines, Jefferson and Cedar. Jahn says the insect could already be in Iowa’s capitol city and remains undetected. Jahn says it’s not been an easy process. “Nobody wants to lose trees,” he says. “Some people get real upset. Sometimes they’re a beloved tree and we’re sensitive to that and we’ll take extra time to explain to those folks, ultimately, we have to make the decisions to keep the entirety of our public safe.”

The city has invested in re-planting, at a rate of one-thousand trees per year. The Iowa Department of Agriculture has instituted a 25-county quarantine to try and slow the spread of the bug. The quarantine prevents moving wood that might be infected. The beetle has already destroyed millions of ash trees in the Midwest.