They infest tender new foliage on both annual and permanent plants, usually in spring or early summer.
Aphids ingest the fluids from tender leaf or stem tissue of the plant, robbing it of nutrients.
Aphids also spread disease by moving from one plant to another. Even without resorting to chemical methods, they're not difficult to get rid of. Look for aphids on the undersides of leaves and on tender new growth. You will notice a yellowing of the leaves on new growth, most often in the spring or early summer months. Aphids are usually found in large colonies, called infestations.