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Hellebore aphid

The sap feeding hellebore aphid is a greenfly that 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

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What is hellebore aphid?

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

Non-pestcide control

  • Where possible tollerate infestations of aphids
  • Squashing the aphids by hand can reduce infestations but may need repeating as it rarely removes all aphids
  • Unfortunately aphid predators are not usually sufficiently numerous in early spring to reduce hellebore aphid infestations

Pesticide control

  • Organic sprays, such as natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg, Ecofective Bug Killer), fatty acids (e.g. Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Organic 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
  • More persistent insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Pest Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug 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 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 virus disease known as hellebore black death

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