Emerald ash borer has been discovered in the city of Mankato for the first time during a routine tree survey done by the Minnesota Department of Agriculture.

EAB is a tree-killing larva that tunnels under the bark of ash trees and feeds on the part of the tree that moves nutrients up and down the trunk.

Mankato residents are encouraged to watch for signs of EAB:

  • Identify ash trees. EAB only feed on ash trees. Ash have branches that come off the trunk directly across from each other, known as opposite branching. On older trees, the bark is in a tight, diamond-shaped pattern. Younger trees have relatively smooth bark.
  • Look for woodpecker damage. Woodpeckers eat EAB larvae and woodpecker holes may indicate the presence of EAB.
  • Check for bark cracks. EAB larvae tunneling under the bark can cause the bark to split open, revealing the S-shaped larval tunnels underneath.
  • Contact a professional. If a tree is believed to be infested with EAB, contact a tree care professional, City of Mankato Natural Resources Specialist Justin Lundborg, or the MDA at [email protected] or leave a voicemail at 888-545-6684.

The city is asking residents to avoid transporting firewood, a top cause of spreading EAB.

Minnesota is highly susceptible to EAB –  an invasive insect – because it has approximately one billion ash trees, the most of any state in the nation.