A Prominent Caterpillar

Top Photo: Black-spotted prominent caterpillar.

Ranger Becca radioed me saying she had located a couple of caterpillars munching on a plant in our Into the Mist exhibit in Catch the Wind. I went out to see if I could identify the beasts.

I knew right away the caterpillars were a species of prominent, they had tail-like projections on their posterior ends. Many of the prominents have these so-called tails which are actually modified anal prolegs.

If you’re having trouble remembering, prolegs are fleshy limbs or appendages on the ventral side of caterpillars and other insects which are present only in their larval stage and which help the larva cling to leaves, twigs, branches or whatever else the larva wishes to be attached to.

When disturbed, the caterpillar can pump blood into the tails increasing their length. The insect may then raise the tails over the body presumably to frighten away a would be predator. The posterior end of the caterpillar now appearing to be the large, head-end of the insect. Predators may have second thoughts about attacking the caterpillar.

Posterior raised after being disturbed by author.

The caterpillars in Into the Mist were feeding on some sort of legume but since only a few chewed leaves remained on the plants I couldn’t determine what the plants were. Knowing what plant a caterpillar is eating can help establish the caterpillar’s identity. Many are very specific about their choice in food.

Legume was good enough though. The coloration and pattern on the caterpillar and legume should suffice to identify this prominent, though prominents sometimes vary in coloration from individual to individual. This one, however, appeared to be rather distinctive, and I knew I’d seen it before.

Luckily I had a photo of this species in my library. It was a specimen brought to me in August of 2010 by summer campers wanting an identification. It was, and is, a black-spotted prominent.

Photo of specimen from 2010 summer camp (note caterpillar is clinging to plant it was feeding on, a legume).

Black-spotted prominents are listed as eating bush clover, clover, lead plant (a legume), locust, sweet clover, wild indigo and other legumes. In fact, this prominent is the only eastern prominent that regularly feeds on herbaceous plants.

This very attractive caterpillar overwinters as a pupa and will eventually become a small, gray-brown moth.

A handsome caterpillar.

Prominents are a family of moths (Notodontidae) which consist of over 3000 species world wide, 137 in North America, and 60 species in the eastern states.

Ranger Becca.

Thanks for keeping your eyes open and pointing these interesting caterpillars out to us, Becca. It’s always fun to discover, or rediscover, the various species that are everywhere around us but often overlooked.

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