Last week I discovered this tiny (4mm long) orange insect on our bathroom window sill. I presume it must have flown in from the horse chestnut trees that surround our flats.
[Note added 2009-09-11: It is a lime aphid, Eucallipterus tiliae (family Aphididae, order Hemiptera). Originally I thought it might be a barkfly (order Psocoptera). However, I recently came across this image by Brian Valentine which is undoubtedly of the same species but which shows the wing veins more clearly. This key, at the National Barkfly Recording Scheme, then showed that the venation pattern is that of an aphid. A more or less random search of aphid images on the web then led me to the correct identification.]
Photos taken in Reading, UK, on 2009-06-28.