I am not a fan of spiny catepillars, so when I saw these guys infesting a bush between our property and our neighbor's I warned everyone to stay clear of them:
I don't like exterminating anything without knowing exactly what it is first, however, so I went online and did some research. Turns out these are oleander catepillars, and those evil-looking black tufts are not poisonous or stinging. They morph into a white polka-dotted moth that resembles a wasp but is also harmless.
What is remarkable is that these catepillars feed only on the oleander, which is a highly toxic plant. I had not recognized the bush they were feeding on as such; I've only read about it in books. Since poisonous plants are not something we want on our property, we're going to have it removed this winter -- after our scary-looking but ultimately helpful little pals have finished using it for their life cycle: