webbing on blackberry

hi folks, I've got a thornless blackberry growing in a pot on my balcony and dreams of eating delicious fresh fruit from a plant which has taken over the whole building.
But no, lovely new growth in the spring was soon knobbled by what appears to be a tiny tiny white moth, the leaves are covered in webbing and very quickly dry out and the plant looks very sad indeed.
I've tried a spray insecticide... who wants to eat blackberries with insecticide ???
also tried in the pot pellet form but neither seem to do any good.
Can anybody tell me what these little moths are called and any tips on how to eliminiate them?

many thanks