That being said, i allowed this guy to stick around since he was already pretty large. I picked off several other from my little kaffir lime trees as they're SUPER small and one caterpillar can defoliate them in a jiffy - and did.
Is that bird poo on my lemon tree? Nope, it's a caterpillar, and check out those horns when provoked!
Part of gardening is managing 'pests' and all the critters in your landscape. Do you let them run amuck and manage themselves? Do you step in and remove certain, less ideal bugs? I try and leave most things alone. The anoles will eat the baby leaf footed bugs, but not quickly enough so i spray them down with soapy/spicy/garlicy water when i can find them. The toads, geckos, skinks and other crawlies do a pretty good job of managing most the other bugs and the birds get the majority of the hornworms and other caterpillars. If i had more than one lemon tree, i'd let all these funny looking caterpillars have their way with the foliage and mature into beautiful butterflies.
But i've only got my one lovely, and i'm not afraid to defend her!