Box sucker

What is box sucker?

Box sucker is a sap-sucking insect, sometimes known as a 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 the foliage
• In April to May flattened, pale green, wingless nymphs live among the leaves at the shoot tips

Control

Non-chemical control

Control is unnecessary on established box hedges or topiary plants that are going to be clipped.

Chemical control

Young plants that need to grow larger can be sprayed with deltamethrin (Bayer Sprayday Greenfly Killer) when newly-hatched nymphs first appear on the new growth in spring. There is no point in spraying later in the spring once the feeding damage has occurred.

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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
• 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