Unknwon caterpillar

Unknwon caterpillar

Observation - Unknwon caterpillar - UK and Ireland. Description: About 10mm long, yellow stripe down back with black protrusion 1/4 of the way down body from head. Has small red markings down the sides and is very hairy. Was found attached to the little cocoon like object (won't let go of it) on a rhubarb leaf. Any ide

About 10mm long, yellow stripe down back with black protrusion 1/4 of the way down body from head. Has small red markings down the sides and is very hairy. Was found attached to the little cocoon like object (won't let go of it) on a rhubarb leaf. Any ideas?