I was speculating idly yesterday on why many Carpet moths and a number of other species often rest with the tip of their abdomen jauntily cocked aloft. Idly, because as usual I had other things to get on with and therefore no time to do research into the question.
I have now remedied that and come up with the entry above on a discussion forum. The first part chimes with my own, unoriginal, thinking but the second is fascinating. I have dealt before with anti-bat radar counter-measures taken by some moths, notably the Yellow Underwings, but not in connection with the curling bodies. I shall follow the links and read more. There are, after all, many sounds in Nature which humans cannot hear.
Meanwhile here is a Red-green Carpet again, this time demonstrating another unusual habit of the species: when surprised - and presumably therefore alarmed - it folds its wings butterfly-style above its back, rather than in the usual flat position shown below.
I shall search again for enlightenment but my guess is that the moth hopes to make itself less conspicuous. This happens in a fascinating way with many of the 'brown' species of butterfly, notably the Graylings, which fold their wings above their backs, slide back the forewing to make the visible area roughly half as big and then, brilliantly, angle themselves against the sun so as to cast the smallest shadow possible. I have spent happy times on warm and sunny days both here in the UK and abroad watching this sensible behaviour.
Lastly, another type of Carpet moth, the Common Marbles's 'copper blotch' form, was sleeping on the wall of our house near the light trap. I don't think its neat placing on the cement pointing is a matter of coincidence, another sign of how moths position themselves in ways which they think and presumably hope make them harder for predators to see.