What are rose aphids?

Aphids, also known as greenfly and blackfly, are sap-sucking insects. There are several species that occur on the above ground parts of roses in Britain. Roses are also host to a root aphid, the root aphid does not appear to affect the health of roses. 

Symptoms

Check your roses regularly for signs of infestation;

• Green or pink insects, cluster on the flower buds, shoot tips and young foliage
• White cast aphid skins are often seen on infested flower buds and leaves
• Flower buds and foliage can be covered in a sticky honeydew that aphids excrete
• Black sooty moulds may grow on the honeydew

Control

Check roses frequently from spring onwards so action can be taken before a damaging population has developed. When choosing control options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section. If this is not sufficient to reduce damage to acceptable levels then you may choose to use pesticides. Within this group the shorter persistence pesticides (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife than those with longer persistence and/or systemic action.

Non-pesticide control

• Where possible tolerate populations of aphids
• Use finger and thumb to squash aphid colonies where practical
• Encourage aphid predators in the garden, such as ladybirds, ground beetles, hoverflies, parasitoid wasps and earwigs. Be aware that in spring aphid populations often build up before natural enemies are active in sufficient numbers and then give good control
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Pesticide control

• Organic sprays, such as natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg, Neudorff Bug Free Bug and Larvae Killer), fatty acids (e.g. Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Plant Guard Pest & Disease Control, Bug Clear for Fruit and Veg) can give good control of aphids. These pesticides have a very short persistence and so may require reapplication to keep aphid numbers in check. Plant oil and fatty acid products are less likely to affect larger insects such as ladybird adults
• Plant invigorators combine nutrients to stimulate plant growth with surfactants or fatty acids that have a physical mode of action against aphids (e.g. Ecofective Bug Control, RHS Bug and Mildew Control, SB Plant Invigorator and Westland Resolva Natural Power Bug & Mildew). These products contain some synthetic ingredients and so are not considered organic.
• More persistent contact-action insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer, Provanto Sprayday Greenfly Killer) and cypermethrin (e.g. Py Bug Killer)
• The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) is also available

Download

Pesticides for gardeners (pdf document)

Biology

Aphids usually overwinter on roses as eggs laid on the stems in the previous autumn. However, in sheltered places there may be active nymphs and adults all year round.

Aphid numbers start to increase in spring when roses are producing new growth and reach a peak in early summer. Some rose aphids are green but a common species, Macrosiphum rosae, is pink. During spring and summer, the aphids are mostly wingless forms, 2-4mm long, that give birth to live young.

Winged forms develop when plants are heavily infested and aphids need to migrate to new host plants.