Catalpa worms

Poor little guys.
Almost every Catalpa worm (Ceratomia catalpae) on this tree had been parasitized by a Braconid wasp (Apanteles congregatus). The wasps lay eggs beneath the skin of the caterpillars, and the larvae feed on the them until they are ready to pupate. (The white cylinders are cocoons, not eggs.)
The wasps do the same thing to tomato and tobacco hornworms, amongst others, so are considered beneficial.
Poor little Catalpa worms, though.

Mightily encumbered.
More than you ever wanted to know about Catalpa worm anatomy is here.