May, 2010

Saltmarsh Caterpillar

If you want to see the adult of this caterpillar, place your cursor over the image

We are having a very wet spring here in central Texas and that means it is a good year for plants AND for everything that eats them. Few insects are more efficient at eating plants than the saltmarsh caterpillar (Estigmene acrea). This moth larva is an aggressive generalist feeder. It will eat almost any kind of plant. It is big, moves fast, and its fuzzy body provides good protection from many predators (although it does NOT have poison in its spines). Being an opportunist in the extreme, this caterpillar will also devour any nearby caterpillars that are slower. It makes short work of butterfly chrysalises too. The advantage of getting a little extra protein is not lost on the saltmarsh caterpillar.

Despite the name, this insect is quite common in many habitats, including gardens and fields in our area. It is well adapted to dry climates and can survive far from marshes, salty or otherwise. It is a member of the family Arctiidae (now sometimes classified as a subfamily, Arctiinae, within the Noctuidae family). This family includes the tiger, lichen, and wasp moths. The saltmarsh caterpillar is a tiger moth; adults do not feed and are generally white with black markings, often having startle colors to ward off predators. Female saltmarsh caterpillar moths have the same orange body as the males but they lack orange on their lower wings.

This caterpillar is frequently mistaken for the woolly bear, which in our area refers to a black caterpillar with red bands, the larva of the giant leopard moth (Hypercompe scribonia). While the woolly bear always looks the same, the saltmarsh caterpillar has a range of colors, from very light yellowish white to almost black. They are usually somewhere in between, with black and yellowish markings along with orange-brown warts on the sides. The extra long white hairs at the front and back are also characteristic.