They feed exclusively on elm leaves, from both native and non-native species. Adults are less commonly seen, but are about a quarter-inch in length, shiny black and winged. According to ODNR ...

Above: Siberian elm samara in New York City. Like other fruit, nut, and winged seed trees (like maples), elms can have mast years, or a bumper crop, where branches appear to be bursting with ...