Things You'll Need
Instructions
Observe the caterpillar you have found. Note its markings and other characteristics. Know that in Michigan there are about 89 different species of caterpillars, so look for distinguishing features in your specimen.
Take note of its color, pattern, hair density and any distinctive features, using a good identification guide. For example, if the specimen you found is green and spotted with sparse hair, you have stumbled upon either Antheraea polyphemus, Eacles imperialis or Heliothis virescens. Look at your caterpillar's particular characteristics in comparison to the ones depicted in your field guide to make a precise identification.
Check to see if your caterpillar will end up morphing into a moth, which is a real pest that needs to be eliminated. One of the more common pests in Michigan is the gypsy moth. Gypsy moth caterpillars are distinguished by pairs of red and blue spots down their backs. if you find one or some of these, eliminate them because over time they do severe damage to trees.