When I first saw this caterpillar I thought, "Wow, that caterpillar looks like bird poop".
Later, I took notice of all those spikes on the caterpillar's head as well as
those odd bumps all over its body. Simply ugly. This is the caterpillar of the White Admiral butterfly... and there is no similarity between the two.
Needless to say, I decided to keep watch over the caterpillar. It's not everyday that I run into a caterpillar disguised as bird droppings... plus, it was right at eye level on a branch of a young aspen in our backyard.
See what happened when an ant came along...
Since the caterpillar was so unusual, and also so conveniently located, I covered the aspen branch with mesh to protect the caterpillar from any sharp-eyed birds or parasitic wasps. The thought was to keep it safe (and confined) until it turned into a butterfly. Shortly thereafter the ugly caterpillar pupated.