I was intrigued with the size differences between the larvae, some had perished and were little bigger than a basmati rice grain, whether they were the shrivelled husk remains of parasitical wasp (Cotesia bignelli) infection or the result of some climatic problem, remains unaswered, but the different instar sizes can be judged by the photographs provided below - using a one pence piece for scale comparison - a one pence piece is approximately 20mm in diameter. Marsh Fritillary caterpillars are 26 to 30mm in length at final instar (5th or 6th ?) and approximately 90% of my count fell within this size, the remainder were considerably smaller - as the middle image below shows.
Another interesting observation was the absolute blackness of the smallest caterpillars compared to the larger individuals which appear to be 'peppered' with white. I've re-read Jeremy Thomas's wonderful essay on the Marsh Fritillary in The Butterflies of Britain & Ireland and realize that there is still so very much for me to learn about this fascinating fritillary. I'm now going to spend time looking for the chrysalis and know that this could prove another challenge...but hey! its great fun isn't it
![Wink :wink:](./images/smilies/icon_wink.gif)
Bill
![Very Happy :D](./images/smilies/icon_biggrin.gif)