Buff Tip moth eggs are laid in batches on various deciduous tree species. The caterpillars feed gregariously in the summer and often defoliate whole branches. The ones shown here are feeding on Hornbeam.
This summer a group of these sawfly larvae have defoliated the top of a small ornamental pine tree in my garden in Bliss Gate. They have been recorded here since 2014. There are still a few larvae present in the middle of September, but they will soon all have moved down into the soil where they spin overwintering cocoons in which to pupate. They will emerge as adults during next May or June.