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 affected by late spring. Damaged leaves are often also discoloured with brown dried up edges to the holes. Affected Viburnum tinus often produces an unpleasant odour 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

Check susceptible plants frequently from spring onwards so action can be taken before a damaging population has developed. When choosing control options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section. If this is not sufficient to reduce the damage to acceptable levels then you may choose to use pesticides. Within this group the shorter persistence pesticides (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife than those with longer persistence and/or systemic action.

Control for viburnum beetle if necessary, should be targeted at the larvae in spring. Adult beetles occurring later in the season cause less damage, can fly into gardens and are more tolerant of control measures. 

Non-pesticide control

• Where possible tolerate populations of larvae and adult beetles
• Remove larvae by hand where practical
• Encourage wildlife in the garden, such as birds and predatory ground beetles who will eat the larvae and sometimes the adult beetles.

Pesticide control

• Organic contact insecticides containing natural pyrethrins (e.g. Bug Clear Gun for Fruit & Veg, Neudorff Bug Free Bug and Larvae Killer). Several applications of these short persistence products may be necessary to give good control
• More persistent contact insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Bug 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

Downloads

Pesticides for gardeners (downloads pdf document outlining pesticides available to home gardeners)
 

Biology

Viburnum beetle overwinters as eggs that are deposited in the bark of the current years growth of viburnums 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.

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.