European Elm Flea Weevil
These tiny black beetles leave “shotholes” in leaves on elm trees. The larvae are actually leafminers and tunnel within leaves creating brown, blotch mines on leaves.
Adults emerge in early spring. Eggs are laid in larger leaf veins and, upon hatching, larvae feed within the leaf. They feed and work their way to the leaf edge. Larvae pupate within the leaves before emerging as adults. There is one generation per year.
Adults chew holes in leaves giving them the appearance as if they were shot with a shotgun. As larvae feed between the leaf layers, their tunnels turn to brown and eventually coalesce to a brown “blotch” mine that ends at the leaf edge. In years when infestations are high, extensive damage can stress a tree, but rarely causes the tree to die.
Natural enemies like birds, predatory wasps and parasitic wasps feed on larvae during the spring which can drastically reduce populations of European elm scale. If populations are really high and causing the tree to appear aesthetically displeasing, there are insecticidal options available.