Hellebore aphid

The sap feeding hellebore aphid can cause a lack of vigour and sooty mould on the leaves and flowers of hellebores.

Hellebore aphid (Macrosiphum hellebori) on Hellebore (Helleborus sp.). Credit: RHS/Entomology.

Quick facts

Common names: Hellebore aphid
Scientific names: Macrosiphum hellebori
Plants affected: Hellebores (Helleborus species)
Main symptoms: Whitish green aphids cluster on the flowers and foliage, which is sticky with honeydew excreted by the aphids
Most active: March-April

What is hellebore aphid?

Hellebore aphid is a sap-sucking aphid or greenfly that can be found on the flowers and foliage of hellebores in spring.

Symptoms

  • Whitish-green aphids, 2-4mm (about 1/8in) long, sometimes form dense colonies on the underside of hellebore leaves and flowers in early spring
  • The sugary honeydew they excrete can also lead to the growth of sooty moulds on the foliage
  • This species of aphid is only found on hellebores

Control

Check hellebores frequently from early 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

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
Follow label instructions when using pesticides
Plants in flower should not be sprayed due to the danger to bees and other pollinating insects
Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Gardening Advice. It is a list of products currently available to the home gardener

Download

Pesticides for gardeners (pdf document)

Biology

  • Although hellebore aphid can be present on hellebores all year round, noticeable populations usually only occur in early spring at flowering time
  • It is possible this aphid may also be responsible for spreading the virus disease known as hellebore black death


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