Gypsy Moth: A Balanced Perspective

The European spongy moth, formerly gypsy moth, is firmly established in the eastern and midwestern U.S. and southeastern Canada. The Asian spongy moth is not yet established in North America, but is occasionally intercepted at ports of entry. Both moth species look the same and have similar biology – the only difference being that adult female European spongy moths cannot fly, whereas adult female Asian spongy moths can. These moths have one generation per year, and larvae feed on hundreds of different tree species. Oaks are preferred, but caterpillars also utilize birch and poplar as food. Larval feeding can completely defoliate trees. A single defoliation event probably will not kill the tree, but multiple successive defoliations can severely weaken trees. Spongy moths lay egg masses on nearly any surface – including cars and trailers – and this is a primary method in which spongy moths are spread.