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Caterpillar Hunt - Saturday May 16, 2009
Ecologist John Lill led a group of 15 adults and children on our second Caterpillar Hunt, this one in the Kemp Mill area just below Colt Terrace. He pointed out that caterpillars are among the fastest-growing organisms in nature, increasing in mass 1,000-fold as they mature from egg to larva. He noted that locally, black cherry and oaks are particularly rich in caterpillar variety, tulip tree less so, with maples hosting somewhat fewer still. The cherry hosts many species even though the leaves produce a form of cyanide that is activated upon chewing. Tent caterpillars, among others, have evolved a metabolism that counteracts the poison. John is an insect-plant ecologist at George Washington University, specializing in forest caterpillars.

John showed us how beating on tree limbs can drop unseen caterpillars
onto a white sheet for easier collecting.

The most abundant species we found was the Eastern Tent Caterpillar. John explained that their "tents" provide a thermo-regulated environment for young caterpillars, cooling them on hot days and protecting them from cold on chilly days. By the time of our hunt, these caterpillars had reached their "wandering" phase, when they abandon the tent to travel far and wide in search of a suitable location to form their cocoons and pupate. As pupae, the insects will undergo metamorphosis yielding adult moths sometime in late June or early July.

Last year we saw a number of Gypsy Moth caterpillars, but this year we found only one.

Our sharp-eyed families found tiny caterpillars in the inchworm family (Geometridae). Numbering in the hundreds of species, this group of caterpillars serves as a staple in the diet of migrating and nesting birds.

The first photo shows an unidentified species, while the minute specimen
on the right is a tulip tree beauty (Epimecis hortaria).

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