A small chunk of leaves fell off of a potted tomato plant. We noticed our cats taking an interest in it once it started moving. Then a little caterpillar poked its head out. What kind of bug is this and should we worry about our plant?
This is the larvae (caterpillar) of a bagworm moth (family Psychidae).
The caterpillar larvae of the Psychidae construct cases out of silk and environmental materials such as sand, soil, lichen, or plant materials.
There are about 240 genera, so I will leave IDing to lower taxonomic levels up to you. However, based on the striations of the caterpillar and your lcoation, the Evergreen Bagworm Moth doesn't seem like a bad guess...