Bugs on my currants

[brooklynodog]

I was hoeing out my fruit cage this afternoon, it contains, blueberries, goooseberries, strawbs, red and black currants. On the currants (both sorts) I noticed some varying sized black caterpillar like bugs with red in there and 2 antenna like things. I cant ID them on the net any ideas if they are harmfull please?

[WrexTheDragon]

Have you a picture????