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Emerald Ash Borer Background Information

Section One

What is the Emerald Ash Borer?

The iridescent adult beetle is dark green in color, 1/2” long and 1/8” wide.  When adults flare their wings, you can see their violet abdomen.  The larvae are cream-colored grubs with flat bodies, bell-shaped segments, and wide heads. 

Recent research has shown that in heavily infested trees or in trees that are stressed, most EAB have a one year life cycle.  In healthy trees that have only a few larvae, most EAB require two years to complete their development. 

Adult beetles begin emerging in middle to late May, with peak emergence occurring during the month of June.  The adult insects are most numerous in late June and early to middle July.  Adults feed on the ash tree leaves, and then females begin laying eggs approximately two weeks after they emerge.

The eggs, laid in bark crevices, hatch in one to two weeks and the tiny larvae bore through the bark.  The larvae remain here for several months, usually from late July through October, feeding on the cambium or vascular tissue that carries water and nutrients to the tree. 

Most EAB remain in small chambers underneath the outer bark over the winter.  Pupation occurs in the spring, and new generations of adults emerge in May to begin the cycle all over again.  More info on EAB website