Caterpillars on Parade

Mourning cloak caterpillar. J. Schaeffer

What's black and white and red all over, travels in packs, covered with spines and eats the willows at Willow Grove Nature Education Center?  The after-school FOX club found them yesterday wandering around the back patio--caterpillars of the mourning cloak butterfly!  With no obvious damage to the willow, each caterpillar had apparently eaten enough willow leaves and was looking for a place to make a chrysalis.  If you missed them, we have a couple in the nature center that we'll be raising to butterflies.

Mourning cloak butterfly.  Bill Hubick

Mourning cloaks are considered uncommon in Maryland.  As caterpillars, they eat the leaves of just a few plants: willow, elm and hackberry.  The adults that emerge in June will rest (aestivate) during the hottest part of the summer, become active again in September.  Only a few insects over-winter as adults, and the mourning cloak is one, sheltering under bark and emerging early in spring or even on warm, sunny days in winter.  The adults typically eat sap, especially from oak, and rotting fruit.  After living almost a year, they mate in early spring; lay communal eggs on the host plant; and the gregarious caterpillars feed inside of a silken web.

So, the official tree of the Willow Grove Nature Education Center is host to what's now the official caterpillar/butterfly--the mourning cloak.