How to Identify a Caterpillar on a Green Bean Plant

Use a notebook to record the months when you see the caterpillars on your green bean plant. Some varieties of moths and butterflies only have offspring once a year, so by taking notice of the seasons that you see the caterpillars, you can narrow down your search.

Examine the caterpillar on your plant with a magnifying glass and note the colors and/or any patterning that the insect displays. Some caterpillars, such as the northern pearly eye, are all one solid shade of green, while others like the imperial moth have a repeated spot marking along the length of the body. Additionally, take a picture of the insect so that you can have it as a reference.

Determine the texture of the caterpillar's body. For example, some species, such as the yellow colored scape moth, have a very thick layer of hair covering the body, but you can find others like the monarch that are completely hairless.

Write down any distinguishing traits that may further identify the caterpillar on your bean plant. For example, some larvae, such as the pine devil, have horns on their head or knobs throughout the body like the unicorn caterpillar.

Access an Internet reference like Discover Life's "Caterpillars identification guide & checklist" to search their database (see References). Using your notes and picture, select the check boxes next to the appropriate caterpillar traits, such as "Hair density," and click the "Search" button. A listing of possible matches appears, which you can click on to get a photo and description. Continue to go through the list until you identify the caterpillar found on your green bean plant.