First of all, i think this is the single most fascinating website I have ever seen. Whenever I visit, I sit and read for hours (much longer than i should). Anyway, last spring my red maple failed to produce a single bud or leaf (I supposed it had died during the winter). No explanation of this tragedy presented itself. This afternoon, however, I was looking around for some foliage for my pets, when I saw that the bark was starting to fall off of the red maple’s trunk. Being extremely curious, I pulled some bark from the tree and found these beetles overwintering underneath. Could you identify them for me? And could they be responsible for my young tree’s demise? Thank you so much,
Annie Baker, Maryland
Thank you so much for your very kind letter. Your beetles are Pleasing Fungus Beetles, probably in the genus Megalodacne. We believe they are Megalodacne fasciata though it is difficult to be certain in a photo. According to our Field Guide to the Insects of America North of Mexico by Borror and White: Pleasing Fungus Beetles “are usually found on fungi or in rotten wood; some are fairly common. Adults hibernate under bark, often in groups.” The beetles are not responsible for the demise of your tree, but they are feeding on the fungus that is assisting in its decomposition.