Caterpillars are commonly found in gardens and parks, and being able to identify different species will help develop your knowledge of these unique creatures. A caterpillar hatches from an egg, and then creates it creates a cocoon for itself. After it has hibernated inside the cocoon, it becomes a moth or butterfly. There are five main types of fuzzy yellow caterpillars found in North America which can be identified according to the amount of fur that appears across its body, its color and location.
Consider the shape of the creature you are looking at. A caterpillar has a small, sausage-shaped body which typically lies horizontally on a leaf or branch. It measure from 1/4 inch to 1 inch in length.
Inspect the creature and look at the way it moves. A caterpillar has a distinct body movement that involves elongating its body then scrunching it up into a bend. It repeats this in order to progress across the surface it is on. Check that you are looking at a caterpillar by checking that it moves in this way.
Confirm where you found the caterpillar. Yellow Based Tussock moths and Definite Tussock moths are only found in the eastern states of the U.S., while the other three yellow species of caterpillar are found all over the U.S. This will narrow down identifying the type of caterpillar you are looking at.
Look at the caterpillar closely. Position yourself within a few inches of the caterpillar so that you can see the texture and color of its body. View it in daylight so that it is clearly visible.
Assess how fuzzy the caterpillar is. Its fuzziness is the amount of hairiness or fur that appears across its body. Yellow fuzzy caterpillars are all covered in tufts of hairs protruding from their bodies. Make sure the creature you are identifying has these.
Check the shade of yellow of the caterpillar, by looking at the color of its body and hair. The Spotted Tussock Moth is easily distinguished from other caterpillars because it is bright yellow with black spots. The Sycamore Tussock moth is a pale shade of yellow, while the Fall Webworm has hair with an orange tinge. The Definite Tussock moth is pale yellow with egg-yolk colored dots across the top half of its body. However, the Yellow-Based Tussock moth is yellowy-brown with dark dots of orange across its back.
Do not pick up or disturb the caterpillar to avoid hurting it or interfering with its natural environment.