Synchronised munching

It was overcast and looked like it was going to rain the entire day so the light was very poor. It was already getting rather late and I was still looking for something to blip when I remembered that I'd seen a large number of caterpillars on a rosebush at the park yesterday afternoon and managed to get a few shots. These two caterpillars somehow made me think of two gymnasts doing a synchronised exercise while they were happily munching away.

When I got home I looked for these caterpillars in the two books that I have but I've not been able to identify them.