The saddleback caterpillar, Acharia stimulea is primarily green with brown at either end and a prominent white-ringed brown dot in the center which resembles a saddle. It has very potent stinging bristles at each end and along the sides.
Saddleback Caterpillar

Gerald J. Lenhard, Louiana State Univ , via
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Bugwood.org via Wikimedia Commons