Subject: What’s this Bug?
Location: Torbay, Newfoundland, Canada
October 4, 2012 8:29 pm
I grew up in Newfoundland, as has my entire family….. none of us has ever seen this bug before. It’s about 4” long and literally reared up at me when I touched it! The forked prong came out of it’s mouth at that time. Weird!
This is a pre-pupal Tiger Swallowtail Caterpillar, and considering your location, it is most likely a Canadian Tiger Swallowtail, Papilio canadensis. The “forked prong” you described and photographed is a defense organ known as an osmeterium. The Osmeterium releases an odor that some predators find offensive and it might also give the caterpillar the appearance of a snake that may discourage getting eaten by a bird.