Viburnum beetle

Viburnum beetle can cause severe defoliation of some Viburnum species, especially V. tinus and V. opulus.

Viburnum beetle damage on guelder rose Viburnum opulus

Viburnum beetle damage on guelder rose Viburnum opulus

Quick facts

Common name Viburnum beetle
Scientific name Pyrrhalta viburni
Plants affected Viburnum tinus, V. opulus, V. lantana and other Viburnum spp.
Main symptoms Foliage with many holes eaten by the larvae and adult beetles
Most active Late April-June (larvae) and late July-August (adult beetles)

What is viburnum beetle?

Viburnum beetle can defoliate viburnums. Most of the damage is caused by the larvae in spring but some further  damage is done by the adult beetles in late summer.

Heavy attacks can result in most of the foliage being severely damaged by late spring. Damaged leaves are often also discoloured with brown dried up edges to the holes created by the larvae and adult beetles. Viburnum tinus can be severely affected and this species when damaged by the beetle often produces an unpleasant smell particularly when the foliage is wet.

Symptoms

  • Holes eaten in the leaves of viburnums, with the larger leaf veins remaining, giving the foliage a lace like appearance
  • Creamy yellow larvae, with black markings and up to 8mm long, are present on plants from April to June
  • Greyish brown adult beetles, 4.5-6mm long, feed on the leaves from late July to September

Control

Non-chemical control

Larvae are normally too numerous to hand pick so attacks may have to be tolerated. Although plants can look tatty they usually survive even the most severe defoliation.  

Chemical control

  • Inspect viburnums during spring for signs of feeding on new foliage. This will indicate when the overwintered eggs are hatching
  • The best time to spray is when the newly hatched larvae are feeding on the new foliage in mid-April to early May. Treatment in mid-summer is too late as the worst of the damage has already been done and only less susceptible adults will be present. Pesticides are likely to be more effective on larvae than adults. 
  • Heavy infestations which are impractical to remove by hand can be treated with pesticides
    Organic insecticides containing natural pyrethrins (e.g. Bug Clear Gun for Fruit or Defenders Bug Killer, ecofective Bug Killer (also contains fatty acids)). Several application of these short persistence products may be necessary to give good control
  • Synthetic pyrethroid pesticides such as lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), or deltamethrin (e.g. Sprayday Greenfly Killer) can be used
  • The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) can also be used 
  • Plants in flower should not be sprayed due to 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

Viburnum beetle overwinters as eggs that are deposited in the bark of stems in late summer. These eggs hatch in late April-early May and the larvae begin feeding on the new foliage. When fully fed in late May-June, the larvae go into the soil to pupate. Adult beetles emerge in late summer and after mating, deposit batches of eggs in the woody stems.

Most of the damage is caused by the larvae during late spring. Adult feeding damage on the foliage is much less extensive than that of the larvae.


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