In Search of Caterpillars

By Tom Allen, Contributing Editor

They may not be flashy, but caterpillars are just as fascinating as adult butterflies. Sometimes, however, these budding "flying flowers" are difficult to find in the garden.

For protection, many caterpillars hide in nests they construct or use camouflage to blend in with their host plants. To spot them, you need to know what to look for.

That's not the case with the monarch caterpillar—one of the most widely recognized species. Brightly marked with yellow, white and black bands, it's usually visible on its milkweed host. The bright colors warn predators of its toxicity, so these caterpillars don't have to hide.

Where to Look

If you plant vegetables such as carrots, parsley, dill or fennel, watch for the black swallowtail caterpillar.

Young swallowtail caterpillars are dark brown or black with a white "saddle" marking on their backs that makes them resemble a bird dropping-an excellent camouflage!

To find the tiny caterpillars of hairstreaks or blues, search for ants on their host plants (like willows, blueberries and chokecherry for hairstreaks; legumes for blues). These plain green caterpillars blend in almost perfectly, but they secrete a sugary solution that attracts ants.

If you have a patch of false nettles, look for the caterpillars of red admiral or eastern comma. In stinging nettles, search for the Milbert's tortoiseshell as well.

All of these caterpillars live in folded leaf shelters that are easy to see. You may have to open the folds to peek at the caterpillar or go out at night with a flashlight-that's when the caterpillars are feeding. All three species will be dark colored with many spines.

Another Good Approach

Here's another way to track down caterpillars in your garden. After you see a butterfly, use a field guide to determine its host plants. Then explore your garden for those plants.

Once you've identified a possible host, search the leaves, flowers and fruit for signs of caterpillar feeding. If you find them, look for caterpillar shelters or the caterpillars themselves.

And don't forget to check your trees and shrubs, too. Sassafras and spicebush are the host plants for the spicebush swallowtail. These caterpillars always fold the leaf along the upper surface, lining it with silk. The shelters are easy to see, and the green caterpillars inside will amaze you with their large false eyespots.

Finding caterpillars can be a challenge, but it's one worth pursuing, especially since the rewards are exciting.