Took some time to recall and find this critter on the net. Been a long time since I came across one of these. It is called a caddisfly nymph. It is in the insect order known as Trichoptera. The larval stage is aquatic and it lives in a case made of sand which it traps using a sticky substance on its body. They can be found in running water or fresh water ponds. The larvae feeds on algae and leaves and is not harmful. The adult has wings and looks like moths.
haha really sorry i seem to be stepping on people's toes lately!
that's not a caddisfly nymph. i've worked with them in field projects and that's not what they look like. plus yup, they're aquatic and you mentioned you found it on your wall?
i admit i don't really know what species of bagworm moth that is, but one of the BP/SC guidebooks simply has it down as 'Wall Bagworm Moth' (i don't have the guidebooks with me now, and I've forgotten which one it is - perhaps Urban Creatures iirc?).
i've seen lots of these in every single corner of Singapore... especially on walls of dusty and forgotten corners. ;p