Saturday, January 28, 2017

A Very Strange Creature

Some insects have strange and unexpected habits. Here is the life story of Anestia ombrophanes, the Clouded Footman moth. On a tree in the park at West Creek I happened upon a small caterpillar (Image 1) about 18 mm long on the trunk of a Eucalypt. It was not feeding or doing anything special. On another tree close by, I saw a strange cage-like structure with a pupa inside which had pink spots like the caterpillar (Image 2). I posted the images on Bowerbird (a nature website), and found that this insignificant caterpillar is a strange little creature indeed.
Image 1
Image 2

Image 3
When the caterpillars are ready to pupate, they shed the irritating hairs (setae) which cover them, and form them into a cage in which they are protected (Image 3). 

When they emerge, the male moth (Image 4), about 10 mm long, is brown and white with yellow hind wings and is normal-looking. He is able to fly, but the female stays on the hair structure until the male arrives to mate with her. She is wingless, a fat little pink and grey legged insect about 8 mm long (Images 5, 6). The male then departs, and she lays several eggs on the hair cage (Image 7), after which she dies. The eggs are thus protected until the tiny caterpillars hatch.
Image 4

Image 5

Image 6
Image 7

I collected a caterpillar and a pupa, keeping them for several days until the adults emerged, fortunately a male and a female. Some eggs were laid before the female died, which I will keep until (hopefully) I have minute pink-spotted caterpillars. They are said to feed on lichen.

Would you ever have imagined this bizarre behaviour? Apparently there are several species of caterpillars which build cages from their hairs, but not all of them have wingless females as does Anestia ombrophanes.
Thanks to Brett from Bowerbird, Wes Jenkinson, and Geoff Montieth for identification and information. Also see the website Coff’s Harbour Butterfly House.

(Article and photos by Glenda Walters)

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