Orchard swallowtail caterpillar everting its osmeterium
A caterpillar with tentacles? The bright red fleshy tubes you see here are known as an osmeterium - the defence mechanism of the larvae of swallowtail butterflies. The caterpillar pictured is the larva of an orchard swallowtail butterfly Papilio aegeus - a common sight on citrus trees. The osmeterium is a gland which emits a very strong smell when everted from the head. I can attest to this as I picked one up and had a good sniff – it's a bit like rotting fruit. It's not all that unpleasant to us humans but would be quite startling to a bird, especially in combination with those bright red tubes.
Size: 2831px × 4256px
Location: Pomonal, Victoria, Australia
Photo credit: © Denis Crawford / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: australia, butterfly, caterpillar, gland, insect, larva, lepidoptera, macro, osmeterium, papiolionidae, swallowtail, warning
