1. UC IPM
Dead (blackish) phloem beneath a row of adult emergence holes in the surface of black walnut bark, showing the longitudinally oriented (with the grain) larval mines of walnut twig beetles, <i>Pityophthorus juglandis.</i>.
Dead (blackish) phloem beneath a row of adult emergence holes in the surface of black walnut bark, showing the longitudinally oriented (with the grain) larval mines of walnut twig beetles, Pityophthorus juglandis..
Credit: Larry L. Strand