from the very neat 'circle' I would say you have leaf cutter bees at work. a lovely find if that's the case. the leaf disc is rolled into a tube and an egg is laid inside where it develops.

Agree its likely leaf cutter bees - it won't harm the Wisteria; in August, most of the whippy growths need pruning right back anyway.

Thankyou for your answers I was getting worried that it might be something nasty that would kill the wisteria and yes I will be pruning in August it has only flowered for the last three years .Many thanks

For as long as I have been on this earth I have seen the leaf cutter bee’s work but have never seen this bee at work cutting the leaf. Has anyone seen this bee actually on the job?

yes I have and I have found the rolled up cocoons with larva in a compost bin in the back garden. I have photos of those but not the adults at work. They were cutting early in the morning ie 6am or there a bouts. it was my climbing rose that was 'attacked'.