Large Rose Sawfly (Arge pagana) larvae
Another species of sawfly on my roses, and I believe these may only be young instars. There are two species of large rose sawfly in Britain, this species being the more common of the two, the other being Arge ochropus. Sawfly have good balancing skills, and to ward off predators they jerk their tail ends around in the air.
The adults, which I have seen flying around the garden, are quite distinctive and have bright yellow abdomens. The female makes a tiny saw cut in plant tissue in which she will lay her eggs. The resulting caterpillars will feed in groups, and they can strip leaves quite rapidly if in large numbers.
Two to three generations of Large Rose Sawfly maybe produced from May to October. They are seen in parks and gardens, also hedgerows, anywhere where rose occurs. Common and widespread.
Photographs taken July 2016, rear garden, Staffordshire.