This little one (1/2" 1.3cm) has been flailing around on the wall for the last couple of days. It is quite small and these photos were the best that i could get detail-wise. It looks to me like a tiny caterpillar in the process of making a cocoon or going through some kind of change...i just can't figure it out, but it is working very hard to do whatever it is actually doing.
I suspect that this could be a larva of a flower/hover fly in the family Syrphidae - see http://www.whatsthatbug.com/category/flies/syrphid-flies/ and scroll down about halfway.
I believe you are right Flap. The images at your link are very close to mine but in a slightly different phase of development i think. This is good news! An aphid eater is always cause for celebration. It disappeared yesterday and hopefully it is off to eat aphids. Thanks very much, now i can keep an eye out for them.
