I went to SW France (close to the Pyrenees) for my holidays this summer and saw an enormous plain-yellow caterpillar crawling over the grass. It was about 9 cm long and the thickness of a man's middle finger, with bands of small blue "beads" along its body. Small tufts of hairs grew from each of the beads. It crawled at an amazing speed. I took some photos and a video of it crawling and can supply these if helpful. Does anybody have any idea what it might have been or know about its biology?
Fabulous caterpillar - this is the caterpillar of the Great Peacock Moth, Saturnia pyri, a close relative of our home grown Emperor Moth, Saturnia pavonia. See UK moths here for more info: http://ukmoths.org.uk/show.php?bf=1643a