Beautiful but deadly! Well, not deadly, but extremely uncomfortable. This saddleback caterpillar, Acharya stimuli,  is bristling with stinging hairs. Potent enough to cause nausea in addition to straightforward pain. Thumb for scale. I followed this specimen over several days as it worked on blackberry leaves. I was excited to find this; I have been looking for one for years. Horticulturists tell me they are not particularly rare; in fact, they would prefer that they were more rare to spare themselves painful surprises. Featured image taken with a Nikon D90 and Micro-Nikkor 60mm macro lens. (Moth image from Wikimedia commons.)

Saddleback Caterpillar, Acharya stimuli, adult, Wikipedia, Creative Commons License