Tomato hornworms are strange looking critters. Stranger still when there are wasp cocoons clustered on them. If you look closely, you can see that some of the cocoons have open ends where the wasps have emerged.
It's actually a very cool bit of nature in play. The hornworms are feasting on my tomato plants (the ones Mr. L. now refuses to feast on because the idea that green monsters crawled around on them grosses him out) and the wasp larvae are feasting on the hornworms. Eventually the wasp larvae would kill the hornworm so it's a natural pest deterent in theory. In reality, the hornworms usually eat the tomat plant bare long before the wasp larvae kill them. Still very cool.