Lilac Ash Borers have been found in ash tree throughout the state of Delaware in early July. These borers normally feed on nectar and lay eggs during their activity period. Frass (sawdust like) around the base of the tree or on the branches can be an indicator of them. Another indicator could also be seeing their skin protruding though a tree trunk or branch. The plants they typically target as hosts are mostly ash trees: green ash, white ash, privet and of course lilac.
Eggs of Lilac Ash Borers are laid either singly or in clusters under cracks in the bark. Lower portions of the tree trunks (ground up to ~12′) or larger branches are often the site of attack. After the eggs hatch, the larvae feeding under the bark and end up creating 2-12 inch deep wounds. With repeated attacks the plants may undergo gnarled swellings, sucker growth and branch dieback.
The adults may be reddish to yellowish or brownish-black with indistinct orange or red bands. They’re similar of paper wasps in size, flight and coloration. Even though they do look like wasps they are actually moths.