Rose bushes may become infected with bugs, such as aphids. While you can buy insecticides at a nursery or garden section of a hardware store, you can also make your own. Use a combination of water and dish soap to kill the insects.The dish soap breaks down the bug's outer layer, which renders it helpless.hile you can buy insecticides at a nursery or garden section of a hardware store, you can also make your own. Use a combination of water and dish soap to kill the insects. The dish soap breaks down the bug's outer layer, which renders it helpless.