Larger Elm Leaf Beetle (Monocesta coryli)
Detailing the identifying qualities of the Larger Elm Leaf Beetle, including physical features and territorial reach.
Updated: 8/29/2017; Authored By Staff Writer; Content ©www.InsectIdentification.org
Some are orange, some are yellow, some have spots, some do not, and sometimes Larger Elm Leaf Beetles are considered a small pest.
Individual Larger Elm Leaf Beetles have a variety of forms. The most recognizable version is yellow with two large brown-black spots on the bottom of the elytra (wing covering) and two lighter spots by the head. As their name suggests, they are found on elm trees where there larval form devours leaves. Hazel, pecan, and birch trees are also a host plant. This species rarely defoliates a large area, but occasional outbreaks happen. It is not as troublesome as other elm-feeding beetles like the Elm Leaf Beetle. Signs of caterpillar presence include the skeletonizing of leaves and a growing brown appearance to foliage, almost as though the leaves were scorched.
Adults stay in the canopy and females lay fertilized eggs on the bottom of leaves. Newly hatched larvae are a metallic red-brown color and they immediately start chewing the fleshy parts of leaves, leaving the thick veins behind. When ready to pupate, they move down the tree into soil and stay there through winter. Adults emerge in the spring. Because only one generation is produced each year, they rarely wreak havoc on a significant scale. When populations are large, however, they are considered a more serious pest. Natural controls like parasites and predators reduce the population the following year, stopping outbreaks from becoming widespread.
Larger Elm Leaf Beetles are found most often in hardwood forests and woodlands that have elm trees in abundance.