A newly hatched scribbly gum moth lays its eggs in Autumn and the larvae develop in the bark through winter.

​

The larvae bore a wandering tunnel under the tree’s bark and the tree responds by filling up the tunnels with cells that are ideal food for the caterpillar. 

​

In summer the larvae begin to moult into their final life stage, developing legs.  They turn around and eat their way back along the tunnels.  When they come to the end they leave the tree and spin a cocoon behind loose bark. 

​

The pupae in the cocoon then slowly changes and turns into a moth.

​

In the photos on the left a  mature Ogmograptis racemosa caterpillar is making a scribble.

 

Source and photos: You Ning Su, CSIRO