You can see in this picture of the skin irritation the wiggle of the caterpillar, as it curled its body. Despite washing the irritated skin right away with warm soapy water, his skin continued to burn and itch with some intensity for two days. The itching has continued for a week or more, and the rash is still quite visible.
Here is the culprit to watch out for, although it appears that it's best to leave all the hairy caterpillars alone. You can see long stinging spikes along the caterpillar's side. When I enlarged the picture further, I could see three more rows of smaller spikes across the back. I would assume there is another row of long stinging spikes along its other side. My Internet research regarding stinging caterpillars states that the caterpillar can dictate the amount of venom it injects, and that in the process of stinging the venom injecting spikes and hairs break off in the skin. Treatment recommendations include repeatedly applying and removing tape to the affected area to pull out the offending stingers. Wash the affected area with soapy water, apply a baking soda poultice and an ice pack. Oral antihistamines may help. In the case of severe reactions a physician's care may be needed.
These caterpillars were in abundance this Spring crawling across the ground. It was funny, but then again, not funny that this little creature and its fellow crawlers had all of us big humans sitting with our feet off the ground and on high alert until they all got to where they were going!