Bagworms are not really worms, but are caterpillars - they are the immature stage of a moth. They're called "bagworms" because they construct bags/cases that are covered with pieces of twigs and/or leaves. The caterpillars feed by sticking their heads out of the top of the bag and chewing on nearby leaves or lichens. They live in these bags until they pupate (also inside the bag). Males emerge a little earlier than females, leaving their bag and flying off in search of a mate. Females emerge eyeless, wingless, and legless! So, she remains in her bag, but emits a pheromone to alert males of her presence. Males locate the females and mate. Once mated, a female lays eggs and dies, leaving a bag full of eggs that will hatch the following spring.
I carefully looked inside of this case and there was a caterpillar in there. It looked reddish, but I couldn't be sure.
On a leaf in a swampy, mixed forest.
Lat: 41.55, Long: -73.22
Spotted on Jun 10, 2018
Submitted on Jul 3, 2018