Viburnum scale

Viburnum scale affects Viburnum tinus and ivy (Hedera), often causing a heavy coating of honeydew and sooty mould. 

Viburnum scale (<EM>Lichtensia viburni</EM>) on <EM>Viburnum tinus</EM>

Quick facts

Common Name Viburnum scale
Scientific Name Lichtensia viburni.
Plants Affected Viburnum tinus and ivy (Hedera)
Main Symptom Honeydew and sooty mould
Most Active Spring and summer
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What is viburnum scale?

Viburnum scale is a sap sucking true bug. It is only found on the foliage of Viburnum tinus and ivy (Hedera)

Adult females are flat, oval, pale yellow and up to 4mm long. Males are 2.5mm long white and elongate oval. In May-June the females become covered with a white fluffy wax coating amongst which the eggs are laid. The crawlers hatch from the eggs in late June. 

Symptoms

Apart from the presence of the insects and the white fluffy eggs masses (in spring) the main symptom is the presence of honeydew on which sooty mould often grows.

Symptoms are superficially similar to cushion scale, however that species rarely occurs on viburnum or ivy.

Control

Viburnum scale insects can be difficult to control, replacing severely infested plants should be considered.

Non-chemical control

Well-tended healthy plants are able to tolerate infestations, although the growth of sooty mould can be unsightly. Physically squashing or removing scales may control light infestations.

Chemical control

The waxy covering produced by scales gives them some protection from insecticides and the best results are achieved by spraying against the newly hatched crawlers in June or early July. 

  • Contact sprays containing deltamethrin (e.g. Bayer Sprayday Greenfly Killer),  lambda-cyhalothrin (e.g. Westland Resolva Bug Killer) or cypermethrin (e.g. Py Bug Killer) can give control if applied thoroughly to the underside of leaves
  • The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) is absorbed into the foliage and taken in by the young scales as they feed
  • Organic pesticides, based on plant oils or extracts (e.g. Vitax Organic Pest & Disease Control Concentrate) or fatty acids (e.g. Bayer Bug free, Doff Greenfly and Blackfly Killer) or based on pyrethrins (e.g. Bug Clear for Fruit & Veg, Defenders Bug Killer, ecofective Bug Killer (also contains fatty acids)) can be used. These are contact in action, have a short persistence and thorough application to the underside of leaves is required. More frequent applications of organic pesticides may be required to deal with the scale nymphs as they hatch
  • Note that dead scales can remain firmly attached to the plants. The success of any treatment can be gauged by the extent to which new growth remains free of infestation
  • 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
  • Do not spray on or near plants in flower due to the danger to pollinating insects

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

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