I got home from work around 3 am and went out back to see how my plants were handling the drought. I found this large furry caterpillar on one of the cypress vines (Ipomoea quamoclit). The caterpillar was roughly 3 inches long. I took several flash photos of it (still pleasantly surprised that I actually got one in focus). The caterpillar didn't appear bothered by this - some species might have immediately dropped off the plant and curled into a defensive ball.
Having a garden in the back yard attracts all kinds of interesting visitors.
UPDATE: Photos on some insect identification sites (bugguide.net, www.whatsthiscaterpillar.co.uk/america) suggest to me that this is probably a giant leopard moth (Hypercompe scribonia). I have checked at night, but haven't seen the caterpillar since the night I first photographed it. I hope nothing ate it.