The purple triangles seen hanging on trees along Adirondack roads are traps designed to lure and capture emerald ash borers (Agrilus planipennis). Emerald ash borers are small (half-inch long) metallic green insects that are coming to us from Asia via Michigan and wreaking havoc on the ash trees of North America.

Recently I wrote a piece on the American elm and its decline thanks to an insect and a fungus. The same thing is happening today with the American beech. But the emerald ash borer (EAB) acts alone. This insect overwinters under the bark of the ash tree (black, green and white ash are all susceptible) and emerges as an adult in the spring. After mating, the female lays her eggs in the crevices of the bark and about ten days later they hatch. The larvae now begin their devastating work, tunneling under the bark, eating as they go. When winter comes, the larvae become dormant, waiting for spring to arrive, at which point they emerge as adults and the cycle begins again. » Continue Reading.