Notes on the Biology and Damage of Two Acrobasis Species (Lepidoptera: Pyralidae) on Black Walnut in Michigan

Acrobasis juglundis (Le Baron), and A. demotella Grote cause extensive damage to black walnut foliage and branchlets, and are potential threats to commercial production of walnut trees in Michigan. Both species are univoltine in Michigan and overwinter in hibernacula. lnstars 1-111 are morphologically indistinguishable between species and have similar feeding habits. In the spring, A. demotella was active about two weeks earlier, caused more damage. and was more abundant than A. juglandis. Five parasitoids were reared from A. juglandis including Trathala plesia (Cushman), a new record. No parasitoids were reared from A. denzotella.