The caterpillar stage of the owl butterfly.  The caterpillars are large

 -- about 5 inches long.

(Butterfly Farm, La Selva Jungle Lodge, Ecuador)

arthropod; insect; butterfly; brush-footed butterfly; giant owl butterfly; caterpillar; larva; Arthropoda; Insecta; Lepidoptera; supF Papilionoidea; Nymphalidae; Caligo teucer, South America