@AlisonMilton : I have taken the liberty of adding a copy of your interesting photo to http://lepidoptera.butterflyhouse.com.au/none/caddis.html I hope you approve? Where did you find this beastie? I would be interested in more photos and information about it.
It was attracted to a light I put out on my back deck in Higgins. This was December last year so I will keep an eye out again this December to see if there is another. Should I collect a specimen?
The larvae are aquatic and make and live in a portable tubular case of either sand grains or plant material. I should have said, if you want a genus or species ID best to leave a specimen at CSIRO Black Mountain Laboratories reception desk for me. (Alice Wells) (Also leave a contact).