Caterpillars Scouting About
Love them or hate them, caterpillars are an important part of the Australian environment. They can bring joy in the form of the promise of a beautiful butterfly, despair as they devour tender young broccoli plants, or itching and pain as a spitfire caterpillar brushes against your bare skin.
Around August, moths and butterflies are busily searching for a safe place to lay their eggs. Some have already produced eggs, so it’s a good time to find out what’s a caterpillar and what’s not.
All caterpillars turn into either moths or butterflies. Australia is home to roughly 370 known species of butterflies, about 10,000 known species of moths, and probably as many moth species again yet to be described.
But some caterpillars aren’t really caterpillars at all. Certain insect larvae are often mistaken for caterpillars. These include saw fly larvae, witchetty grubs, leaf beetle grubs, ladybird larvae, cherry slugs and Bardee grubs. The way to tell the difference is to check out the legs. Caterpillars have sixteen legs: six true legs plus an extra ten small legs called prolegs. Insect larvae on the other hand only have six legs.
Be on particular lookout for spitfires in your backyard. These often gorgeously coloured caterpillars don’t actually spit but rather, have pockets of stinging spines that they stick out when they feel threatened.
Caterpillars in the family Papilionidae and Lasiocampinae have a different defence: they can suddenly produce a pair of soft ‘horns’ from behind their head which make a pungent, aromatic smell but are entirely harmless. The everted horns make the caterpillar look a little like a lot like a friendly Scottie terrier!
DID YOU KNOW?
Caterpillars are great escape artists. Although they don’t have the luxury of running away from a predator, they can bungee jump instead! When threatened, many caterpillars drop off the leaf but remain attached by a fine piece of silk. When the coast is clear, they can climb back up to safety.
Get to know the local species of butterfly in your area, and establish plants in your garden which will provide food for their caterpillars. The local native plant nursery will be able to advise which are the best species. If you live in Queensland, don’t plant the South American Dutchman’s Pipe Aristolochia elegans - the rare Richmond Birdwing butterfly mistakes this plant for the native vine on which it normally lays its eggs - but the exotic vine is poisonous to the caterpillars.