Insects, such as aphids, Japanese beetles and leafhoppers, love munching on roses and flowers, and can quickly destroy prized plants. Unfortunately, most chemical applications kill beneficial insects along with the bad guys, and are toxic to pets, wildlife and humans in large doses. Even organic insecticides, such as rotenone, pyrethrum and insecticidal soap must be used carefully and should be considered toxic. Integrated pest management strategies, such as planting pest-resistant varieties and promoting beneficial insects are a safer bet.
Natural methods of pest control should always be considered first. A hose quickly destroys aphids and other soft-bodied insects, especially those found under leaves. Some plants, such as English lavender, penstemon, dill, sweet alyssum and columbine provide food for ladybugs, lacewings and other insects that eat plant-destroying bugs.
Organic pesticides, including insecticidal soaps, pyrethrum, and rotenone, are derived from natural ingredients or even plants. Even though these products are labeled for organic use, they often kill beneficial insects along with the bad guys. Additionally, they may be toxic to fish, and even pets and people, in high amounts.
Synthetic pesticides work by disrupting the nervous system, causing paralyzation. All should be considered potentially toxic and used very carefully. Chemicals may drift if applied during windy days or be washed into streams or lakes if used near water.
The possible negative effects of using pesticides, including killing beneficial insects, birds and fish, and polluting groundwater, should be weighed against the potential positive effects. Often, insect infestations may cause minor cosmetic damage that prudent gardeners choose to live with, rather than resorting to toxins. Choosing pest-resistant plants is usually simpler than dealing with high-risk plants that are continually plagued by insects.
Gardeners must positively identify pests before applying treatments, because methods may vary depending on the insect. Randomly spraying roses and flowers without identifying the pest will most likely result in an ineffective treatment, as well as possible adverse effects from chemical use. Field books or local county extension offices are good sources for identifying pests and prescribing treatments.