Spray plants with a hard stream of water to control low levels of insects such as aphids or spider mites. These are chemicals of low or least toxicity that have very little environmental impact. Insecticidal soaps are very effective in controlling aphids and other soft-bodied insects. Horticultural oils are effective against many insect and disease pests such as spider mites, aphids and powdery mildew. Lady bugs naturally feed on aphids and often can consume 100 - 300 aphids per day.
Green lacewings are another biological control.
They feed on aphids, whiteflies, mites and thrips. Be aware, however, that eradication of pest problems will not occur when using biologicals. It is also very difficult to keep a released biological in the area you want it in. For example, lady bugs may eat a few aphids in your yard and leave in search of more food. It is virtually impossible to keep purchased biologicals in your yard once you release them.