Insect of the week – White Stemmed Gum Moth

By Huw Morgan

8 June 2012

2 minute read

White Stemmed Gum Moth (Chelepteryx collesi)

By Kim Pullen – Australian National Insect Collection

A huge caterpillar covered in tufts of black spines is not something most people would feel encouraged to touch, or even go near. But the habits of the White Stemmed Gum Moth (Chelepteryx collesi), together with the fact that it lives in nearly all the cities of south-eastern Australia, mean that every year a number of people suffer uncomfortable encounters with this native insect.

The caterpillars can grow to about 12cm long. The moths can be 16cm across the wings.

During spring and early summer the caterpillars are out of sight, eating gum leaves up in the large trees. Having grown all they can, they then wander in search of a place to spin their cocoons – that’s when you can accidentally tread on one.

The short spines are not only sharp and brittle, meaning they will break off and lodge in your skin; they also carry a toxin that causes pain and, in rare cases, anaphylactic shock. Even the cocoon is nasty, since the caterpillar inside sheds the spines and forces them out through the tough silken walls, resulting in a well protected pincushion. These hazardous objects can be on tree trunks, in firewood or even in letterboxes!

The cocoon.

Adult White Stemmed Gum Moths emerge from the cocoon in autumn. They have marbled brown wings and are so big they have been mistaken for bats.