You can spray it with an insecticide, the RHS site suggests the following "spray the plants with deltamethrin (Bayer Sprayday Greenfly Killer), lambda-cyhalothrin (Westland Plant Rescue Fruit & Vegetable Bug Killer) or thiacloprid (Bayer Provado Ultimate Bug Killer). Organic gardeners can use pyrethrum (eg Py Spray Garden Insect Killer, Doff All in One Bug Spray, Scotts Bug Clear Gun for Fruit & Veg). Pyrethrum should control newly hatched larvae but will be less successful against the adult beetles." If I encounter a bush attacked like this I give it a good prune, spray the remaining foliage with an insecticide, and then feed the shrub and water it at the base to give it the best opportunity to grow new leaves. You will need to spray it fairly regularly to control the adult beetles before they lay their eggs again.