Friday Fun Fact – Osmeterium

osmerterium

The Osmeterium is a defence mechanism that all Swallowtail butterfly caterpillars have. Swallowtails are the big butterflies like Cairns Birdwings, Orchards and Ulysses. The osmeterium is an organ above the head of the caterpillar in the first body segment. If the caterpillar feels threatened, two bright red or orange horns pop out, as well as […]