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.

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?

Box sucker is a sap-sucking insect, also known as box psyllid, that feeds at the shoot tips of box plants in spring.

Box can suffer from a number of other problems.

Symptoms

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

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-chemical control

Regular clipping helps remove affected parts of the plant.

Chemical 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
  • Plant invigorators (e.g. SB Plant Invigorator) or organic sprays containing natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg), fatty acids (e.g. Doff Greenfly and blackfly bug Killer) or plant oils (e.g. Vitax Organic Pest & Disease Control) may have some effect. Synthetic products include the contact action pyrethroid insecticides deltamethrin (e.g. Sprayday Greenfly Killer) lambda-cyhalothrin (e.g. Westland Resolva Bug Killer) and cypermethrin (Py Bug Killer). The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) is also an approved product
  • 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 in April
  • 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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