September is a good month for spotting caterpillars. Many overwinter as pupae so they are eating up everything in sight. I use Caterpillars of Eastern Forests published by the U.S. Printing Office as my guide along with Peterson First Guide to Caterpillars.
Spotted Apatelodes Caterpillar (Apatelodes torrefacta)
This caterpillar was on our rusted gate--about 2 inches in length.
Hickory Tussock Moth Caterpillar (Lophocampa caryae)
Right above the gate, I saw this tussock moth caterpillar which prefers hickories and walnut trees, all of which were in abundance here.
Giant Leopard Moth Caterpillar (Ecpantheria scribonia)
This large, about 3 inch in length caterpillar looks scary enough. It rolls into a ball when threatened, exposing the red rings which make it easy to identify.
Monarch Butterfly Caterpillar
This is also a prime time to see Monarch Butterfly caterpillars. This caterpillar will pupate and then emerge and fly south to Mexico before winter! I watched one for a day or two, then it disappeared or was this one about 3 feet away. This one also disappeared after a couple of days--not sure if there's a chrysalis around but I can't find it.
This isn't a caterpillar but a little stick bug--only about 3 inches in length. It should be on a brown blade of grass to be camouflaged but I spotted it easily on these ferns.