Thousand Cankers Disease: What to Do If You Suspect It

​​If you suspect that an insect you have found on or near a black walnut tree is a walnut twig beetle or that you have found damage caused by thousand cankers disease:

  • Collect any suspect insect(s), both adults and larvae, if possible.
  • Place them in a vial or small jar and cover it with 70 percent ethanol or plain rubbing alcohol as soon as possible after collection.
  • Collect the affected branch if possible.
  • Take photographs, if possible, showing the crown of the tree, partially peeled branch to show cankers and adult and larval insects.
  • Call (​608) 224-4745 or email