Box sucker

Box hedges and topiary are often affected by box sucker, although the damage caused is usually superficial.

Box sucker damage. Credit: RHS/Science.

Box sucker damage. Credit: RHS/Science.

Quick facts

Common name Box sucker
Scientific name Psylla buxi
Plants affected Buxus sempervirens
Main symptoms Leaves at the shoot tip are cupped. In late spring, flattened pale green insects and a white waxy substance are present
Most active April–early June

What is box sucker?

There are several species of sucker or psyllid that can be encountered by gardeners, they are sap sucking true bugs. Box sucker feeds at the shoot tips of box plants in spring.

Box can suffer from a number of other problems.

Symptoms

  • In spring a white waxy substance covering a droplet of liquid, excreted by box sucker nymphs often spills from the cupped leaves, leaving white waxy smears on foliage
  • In April to May flattened, pale green, wingless nymphs live among the leaves at the shoot tips
  • New shoot extension in spring is stunted and the cupped leaves at the shoot tips produce a cabbage-like appearance

Control

Damage from this insect is superficial and control is not usually necessary on established box hedges or topiary plants that are going to be clipped.

Non-pesticide control

Regular clipping helps remove affected parts of the plant.

Pesticide control

If damage is serious to plants that need to grow larger they can be sprayed with insecticide.

  • Pesticide sprays are likely to be most effective when newly-hatched nymphs first appear on new growth in spring
  • There is no point in spraying later in the year once the feeding damage has occurred
  • 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 sucker insect nymphs. These pesticides have a very short persistence and so may require reapplication to keep suckers 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
  • Do not spray near plants in flower 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

  • Box sucker overwinters as eggs on its host plant. These hatch in spring when new growth begins 
  • The nymphs suck the plant's sap and secrete chemicals that stunt new growth and distort the leaf shape, although this damage is not usually serious 
  • The nymphs excrete a sugary liquid called honeydew that is coated with a white waxy secretion from their bodies
  • Yellowish brown winged adults, 2-3mm long (1/8in), develop in May to June
  • No further damage occurs after June


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