The emerald ash borer (EAB) is an exotic beetle from Asia that was discovered feeding on ash (Fraxinus sp.) trees in southeastern Michigan in 2002. EAB is responsible for killing over 30 million trees in the northeastern United States and Canada. Beetle larvae feed under the bark and outer sapwood of the ash tree, producing galleries that eventually kill branches and entire trees.

In Chicago, ash makes up around 17% of the City’s street tree population or about 85,000 trees. When adding an estimated 300,000 ash trees from private property to the total, ash trees become one of the most numerous trees in the City.

The City has hired and trained 26 general laborers to implement a multi-year plan to combat the insect which threatens approximately 85,000 of the City’s parkway trees.  Dedicated Forestry crews are working city-wide to inject trees to slow the progression of the insect and manage tree mortality.  Crews will treat 35,000 ash trees this year and another 35,000 next year.  Every three years, our crews will go back to assess the health of tree to determine whether we will retreat the tree or remove the tree.

Residents should consult with an International Society of Arboriculture (ISA) certified arborist to determine the best management solution for ash trees on privately owned property.

The Bureau of Forestry is currently monitoring EAB activity in the City.  If you suspect you have emerald ash borer please call 311 or the beetle hotline, 312.74.BEETL (312.742.3385).