Emerald Ash Borer
Host Trees

Scientific research has concluded that the emerald ash borer feeds and reproduces almost exclusively on ash tree species in North America; with the exception being privet, Ligustrum Spp. Host plant studies, however, have shown that the emerald ash borer is not able to successfully complete its lifecycle on privet alone. Thus, the four native species of ash in Wisconsin, white (Fraxinus americana), green (F. pennsylvanica), black (F. nigra) and blue (F. quadrangulata) are the only hosts susceptible to this pest.

Ash trees are abundant in Wisconsin, with estimates as high as 727 million trees in forests and over 5 million in urban areas. Ash is a component of three forest types in Wisconsin including 1) Elm / Ash / Cottonwood, 2) Northern Hardwood and 3) Oak / Hickory.

An ash tree is most easily identified by its opposite branching pattern (two branches come off the main stem, one on each side and opposite each other) and compound leaves with 5-11 leaflets. Leaflets are moderately toothed and may be stalked or sessile.

To properly identify ash trees, use the following criteria  [PDF, 627KB].