Not sure what the bush is, but Neem oil is a really effective, natural pesticide. Mix it with water and a little washing up liquid (to make it stick to the leaves) and spray it on. It, apparently, alters the brain chemistry in little critters to stop them feeding or reproducing. I had a large infestation of white-fly on my chilli plants and Neem Oil was the only thing that worked.
It's not too expensive so may be worth a try.