Hoot Owl Karma has introduced us to some pretty crazy caterpillars over the past year, most famously Hickory Horned Devil, and most recently Orange-striped Oakworm, but this Labor Day lepidopteran may just be the craziest cat of them all.
Acharia stimulea, commonly referred to as the Saddleback Caterpillar, is a member of the limacodid moth family (slug caterpillars), and it is one of only a few North American "cats" whose "bite" is every bit as bad as its "bark".
The white-ringed, saddle-shaped brown spot in the center of its back is the source of its common name, and stiff, hairlike structures, called setae, growing from its fleshy "horns," are interspersed with venomous spines which can cause a stinging or prickling sensation, severe skin irritation and even nausea.
This individual was traversing the upturned underside of a leaf in the shrubs at Grandma Judy's house, and were it not for Judy's keen eyes, this cool but diminutive critter would surely have gone completely unnoticed.
Not an early instar (larval stage), but judging from its relatively small size of perhaps 0.3 inches, this gal has most likely not attained its penultimate instar status yet. It will soon develop a pair of eyespots on its forehead and its appetite will grow with its increasing girth until the final instar gorges itself to capacity and forms the cocoon in which it will overwinter before emerging in spring as an adult moth.