Hellebore aphid

One of the most important problems of hellebores is a sap feeding aphid or greenfly. It can cause a lack of vigour and unsightly, sooty mould on the leaves and flowers.

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

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?

A sap-sucking aphid or greenfly that infests the flowers and foliage of hellebores in the 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

Non-chemical control

  • Squashing the aphids by hand can reduce infestations but often needs repeating as it rarely removes all aphids
  • Unfortunately aphid predators are not usually sufficiently numerous in early spring to reduce hellebore aphid infestations

Chemical control

  • Organic sprays, such as natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg, Defenders Bug Killer, Ecofective Bug Killer (also contains fatty acids)), fatty acids (e.g. Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Organic Pest & Disease Control, Origins Bug Control) can give good control of aphids. These pesticides have a very short persistence and so may require reapplication to keep aphid numbers in check
  • More persistent insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Pest Killer), deltamethrin (e.g. Ultimate Fruit & Vegetable Pest Killer) and cypermethrin (e.g. Py Bug Killer)
  • The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) can also be used
  • Plants in flower should not be sprayed due the danger to pollinating insects
  • Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener

Download

Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Biology

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


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