Where did the emerald ash borer come from? How has the EAB become so destructive so quickly? How does it kill?
It turns out it’s not the iridescent green adult beetles that do the damage; it’s their larvae, tunneling through the wood in S-shaped patterns called galleries that cut off the channels that transport water and nutrients from roots to leaves. Since this damage goes on under the bark, you may not know it’s happening until the tree is too far gone to save.
“Emerald ash borer can reproduce at high rates in our bountiful ash population,” Dierich says, with female beetles laying 30 to 60 eggs in their yearlong lifespan. Multiply that by millions of beetles in millions of trees, and you’ve got a lot of beetles.
“In the case of Chicago land, most trees are in high EAB-populated areas,” Dierich says.