I have two of these guys on my Penta. They are 3″ long. Brownish gray with great looking “eyes” on the head followed by smaller eyes down each side. I am in N. Texas. I am thinking they are some kind of moth, maybe??
Your caterpillar will become a moth…the tersa sphinx moth…a really cool moth!
This moth is found in the eastern part of North America into the southwest and south to Central America.
The moths feed flying at dusk on nectar from long tubular flowers. The males are sometimes found at lights at night but usually not the females.
Larvae love Pentas, but also feed on catalpa, Rubiaceae or madder family, Manettia sp., false buttonweed, and Heimia salicifolia – a loosestrife found in TX. These caterpillars can be green or brown. This is a large late instar larva that is ready to pupate. They head to leaf debris or loose soil to turn into cocoons for the winter.