Aphids are a common pest in roses. They are very tiny--you might not even see them if you do not look carefully. Aphids vary in color from light pink, brown, or orange, to dark brown and black. Mild winters increase the likelihood of a heavy aphid infestation. Keeping track of the levels of aphid infestation is important to control the spread of disease and make sure your plant's natural defenses can fight them.
Aphids do not have a large range. They remain in the general radius of a single plant or group of plants their entire lives and overwinter to lay their eggs at the base of the plants. Heavy mulching helps to conceal and protect them. Plant debris left over from a previous season makes perfect winter housing for aphids and their eggs. Be sure to remove all dead plant material from the garden and bury or burn it far from the area.
Aphids feed on the delicate rose pedals leaving a marred plant appearance. They also release honeydew. Honeydew attracts other pests and mold and fungus grows on the honeydew further destroying rose petals. Aphids carry viruses on their bodies and legs from plant to plant. When aphids bite plants, the disease invades.
Roses release chemical defenses that combat aphids. If healthy, most rose bushes can fight normal levels of infestation without any help from you. Problems arise when infestations of aphids are heavy, or aphids carry disease in and weaken the plant further.
Beneficial insects are a great natural defense against rose aphids. Ladybugs and lacewings are great defense against aphids. Release beneficial insects in the garden in the spring and so they attack the aphid grubs as they hatch. This is the best time to prevent infestation of problem pests.
Watch out for ants around rose bushes. They do little damage themselves to the plants, but they love aphids for their honeydew and protect them from beneficial insects.
To get rid of aphids yourself, start early in the morning and shake rose bushes by hand. Repeat at night before dark. Follow shaking in the morning with spraying all of the leaves with a soap/water solution. Vigilant aphid duty keeps the pests under control and in manageable levels for the plant's natural defenses to fight during heavy infestation periods. Under normal levels, roses do not need much help dealing with aphid populations.