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 In  spring a white waxy substance produced by flattened pale green insects can be evident. Leaves at the shoot tip are cupped
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, damage is usually minor and can be tolerated.

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 can be 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.

Check box plants frequently in April and May so if necessary, action can be taken before a damaging infestation 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.

Non-pesticide control

  • Often suckers do not affect the growth or vigour of plants and so can be tolerated
  • Regular clipping removes affected parts of the plant
  • Encourage predators and other natural enemies of suckers, in the garden, such as birds, ladybirds, wasps and ground beetles.

 

Pesticide control

  • Pesticides are unusually not needed to control this insect, only if damage is serious to plants that need to grow larger should any treatment be considered
  • Organic sprays, such as natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg, Neudorff Bug Free Bug and Larvae Killer), fatty acids (e.g. Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Plant Guard Pest & Disease Control, Bug Clear for Fruit and Veg) can give good control of suckers. These pesticides have a very short persistence and so may require reapplication to keep sucker numbers in check. Plant oil and fatty acid products are less likely to affect larger insects such as ladybird adults 
  • Plant invigorators combine nutrients to stimulate plant growth with surfactants or fatty acids that have a physical mode of action (e.g. Ecofective Bug Control, RHS Bug and Mildew Control, SB Plant Invigorator and Westland Resolva Natural Power Bug & Mildew). These are not considered organic
  • More persistent contact-action insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer, Provanto Sprayday Greenfly 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. 

Plants in flower should not be sprayed due to the danger to bees and other pollinating insects.

Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Gardening Advice. It is a list of products currently available to the home gardener.

Download

Pesticides for gardeners (link downloads 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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