Black caterpillar - unidentified

[kingrichard]

This might prove tricky as I didn't have a camera with me.

On Brownsea Island on a hazel sapling we saw about fifteen of these black caterpillars. Small in size, two centimetres in length and very thin. No obvious markings down the body but a lime green/yellow head/tail. When we got near or cast a shadow over them they are reared up and waved the green-tipped end at us.

I've had a look on some ID sites and cannot find anything close.

[healfdan]

Could be Sawfly larvae as they adopt the defensive posture you describe.