How to Find Out the Species of a Caterpillar

Take a close-up picture of the caterpillar. This will help with identification later by enabling you to examine the details at your leisure. Place a familiar object, such as a coin, next to the caterpillar and take a picture of them together to establish the caterpillar's size. Obviously, caterpillars grow, but each species has a maximum size.

Examine the plant the caterpillar is feeding on. This can be crucial to identification, as most caterpillars feed only on a small number of host plants. A caterpillar eating the leaves on an oak tree, for example, could belong to one of only a very limited number of species.

Note the caterpillar's movement. Does it crawl, or does it make looping movements?

Note whether the caterpillar is alone or with others and whether they have made a silk tent in the surrounding leaves.

Refer to a comprehensive guidebook to the butterflies and moths of your region that shows the larvae. Create a list of potential species to consider, then narrow your list.

Narrow your list by eliminating all the species of caterpillars that have different physical characteristics than the one you want to identify. If you have a furry brown caterpillar, for example, you can eliminate all the caterpillar species with smooth skin and all the brightly colored ones.

Eliminate species that move differently than the one you want to identify.

Eliminate caterpillar species whose maximum size is smaller than your caterpillar.

Eliminate species that do not feed on the host plant where you found your caterpillar.

To make a final identification, compare your picture to the pictures of the remaining caterpillar species in the guide; at this point, there should now be only a few remaining. Your notes on how the caterpillar moved, the number of caterpillars clustered where you found yours, and the presence or absence of a caterpillar tent may come in useful.