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.

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
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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. Bayer Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Organic Pest & Disease Control, BugClear for Fruit & 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
  • More persistent insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Pest Killer), deltamethrin (e.g. Bayer 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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