Tracy took these photos of Glanville Fritillaries at Compton Down on 08/05/2026 and sent them in as she had noticed they appeared to be deformed and were also very tiny compared to others.

Tracy asked if we could offer any guidance as to the reason for these deformities so I referred her photos to one of our “verifiers” who has commented as follows:

“It’s very difficult to say if this is a case of the wings not enlarging and setting hard after emergence or actual deformities caused by inbreeding. There are many factors that affect whether wings properly enlarge – a butterfly needs to hang upside down, in warm, not too windy weather. It could be that conditions were not good when they emerged, perhaps too cold and windy so they got blown down into the grass and wings set hard before they could enlarge properly.  

The missing antenna could just be bird damage as there is some still there rather than complete absence”.

It would be helpful if anyone visiting Compton Down looking for Glanville Fritillaries who sees any of them with wing deformities would report them to us at the Dorset Branch of Butterfly Conservation (with a photo if possible) at https://www.dorsetbutterflies.com/gallery/ 

If we do get further reports of this deformity, it would increase the chance that inbreeding was the cause.

Editor’s Note:  My thanks to Nick Urch for providing the information for this response to Tracy’s question