When is Bird Poo Not Bird Poo?

Growing up in Phoenix in the 1960s, I would see hundreds and hundreds of butterflies in our backyard. Fast-forward to the new millennium and we see very few butterflies in Phoenix. I still see them, but they number in the dozens, not hundreds.

Today, for the first time in many years, I saw on our tangelo tree the same kind of caterpillar (pictured) I used to see on the citrus trees in our backyard when I was a kid. I think it is the caterpillar of the giant swallowtail. Isn't it neat? Looks just like a strip of bird poo. Evolution has afforded this little bugger a safe haven by disguising it as poo. Who would want to eat poo?

You can read more about the giant swallowtail butterfly here.