Peppermint Stick Insects

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As you walk along the Dubuji boardwalk through the rainforest wilderness leading to the beach at Cape Tribulation, you pass through tall vegetation bordering areas of swamp. Clusters of narrow strap-like leaves with sharp-toothed edges sprout from the ground with their roots in the water. These belong to the largest sedge in Australia, reaching up to 2 metres high, and are called Scirpodendron from the word ‘scirp’ which means ‘to tear’ because they form a razor-sharp barrier along the edges of freshwater swamps.

Looking closely at the inner surfaces of these leaves you are likely to make an amazing discovery because nestled and camouflaged in the shelter of these leaves are large bright green stick insects. Sometimes alone and sometimes in mating pairs. The male is a darker colour and much smaller. If you disturb these creatures, they will squirt out a defensive liquid scented like peppermint that can cause skin rashes and eye irritation in humans. The peppermint stick insects are reputed to be confined to the leaves of pandans which have similar- looking strap-like leaves.  There are three species of the Pandanus tree or shrub at this site. The peppermint stick insects only live in near-shore Pandanus species. However, the insects which I spotted seemed to be on the sedge leaves rather than the Pandanus because the leaves arose in clusters from the ground and not from a stem or trunk. I could be wrong, of course.