EASTERN TENT CATERPILLAR II

Our Caterpillar of the Week is the Eastern Tent Caterpillar -- Malacosoma americanum.

Many of us are familiar with the spongy egg masses of the Eastern Tent Moth, which often encircle branches of wild black cherry trees. However, few realize that even as the snow comes down and temperatures plunge below zero, hundreds of tiny caterpillars are already fully formed within these masses, snug inside their individual egg shells.

Tent caterpillars develop shortly after their eggs are laid in early summer and then go dormant until the following spring. Throughout winter, the tiny caterpillars protect themselves from cold by producing high levels of glycerol--a sugar that acts as an antifreeze--and by reducing their overall moisture content. Still, it's truly astounding that they can survive the extreme weather of a New England winter.

As temperatures warm in spring and cherry trees' buds begin to swell and open, the tent caterpillars are ready to hatch. They arrive first on the scene, taking advantage of the emerging banquet. Some colonies will hatch earlier than others, risking a late, prolonged freeze. This spring, those adventurous caterpillars were killed by unseasonably cold weather in March, but in other years they can thrive and outcompete more conservative colonies.

We find egg masses and bring them into the warm Caterpillar Lab space as soon as we have food available for them. The eggs hatch within a few days, sometimes even within hours, and the tiny caterpillars begin to explore the surface of their foamy egg mass.

- Sam Jaffe TCL Director

Each week (or at least SOME weeks!) The Caterpillar Lab features a "Caterpillar of the Week." Each featured caterpillar is a species we've raised at our lab in Keene, NH. We hope you enjoy meeting the caterpillars of New England!