Clump close to the ford by the River Rib. Clump now lost due to verge cutting. In flower early May
Common British name: Green Carpet Moth
Common British name: Muslin moth. This specimen was a male due to darker brown wings
From close inspection of the pattern, shape and position of the dots, I think this is a female
I found this caterpillar on our climbing rose on Saturday. It's bold markings and four yellow tufts were striking but I didn't know what species of moth or butterfly it was. A twitpic on twitter and a posting on the Amateur Wildlife Film-makers Network didn't take long to produce an answer - Jan Atkinson (@kittiwake70) and Stewart Canham came to my aid with it's identification as the caterpillar of a Vapourer Moth. Stewart added another fact - that the female moth was wingless, so with my interest piqued I did a little more research.
The Vapourer Moth, Orgyia antiqua from the family Lymantriidae, can be found in most of the UK with higher numbers in the south. Male Vapourer's are daylight flying moths, easily confused with a small brown butterfly. The caterpillars emerge in April and May and feed on deciduous trees and shrubs - my guess is it is making a good meal of my climbing rose, eating below the bud in the picture above.
After pupation, the Vapourer's lifecycle differs dramatically depending on its sex. The female is flightless and remains close to its silk enclosed glossy black and hairy cocoon for its short life, releasing a pheromone to attract the flying males. Fertilised eggs are laid on the pupal cocoon and overwinter before emerging the next spring.
The males have dark, orange brown wings with a white, comma shaped spot on each wing and are predated by dragon and damselflies. As Stewart suggested, it is tempting to capture it and watch it pupate as the female (if it was one) would make an interesting photograph. Instead I think I will let nature run it's course and have a nose around for a cocoon site in the wild - you never know, I might get lucky!
References - with some great additional photos of all the lifestages
Wikipedia - Vapourer Moth
UK Moths - Vapourer Moth
Natural England/The Plant Press - Vapourer Moth