Q What is box sucker?
A Box sucker is a tiny insect, also known as a psyllid. It feeds by extracting sap from leaves, leading to distortion.
Q What damage does it do?
A Immature box suckers, or nymphs, feed on young shoot tips. They secrete chemicals into the plant which prevent the shoots developing properly — the leaves become curled and congested, looking like little Brussels sprouts on the shoot tips.
Q How do I recognise it?
A You need to look carefully among the leaves to see the insects themselves. The nymphs are pale green, less than 2mm long, and their bodies are flattened like a bed bug. You may also see patches of sticky honeydew, which often attracts sooty mould. The nymphs also produce quantities of a white, waxy secretion, which can accumulate on or around the plants.
Q What plants does it attack?
A Box sucker only attacks box plants. A different species of psyllid, apple sucker, attacks apple blossom, and other types of sucker can damage bay, elaeagnus and eucalyptus.
Q How serious is it?
A On regularly clipped plants the damaged shoot tips will normally be removed, so the damage is not serious. It can be more of a problem on young plants, or developing topiary, as the distorted shoots retard normal growth.
Q What is its life cycle?
A The sap-sucking nymphs are most abundant in April and May. They mature into winged adults from late April to June and eggs are laid on young stems in late summer. These overwinter and hatch the following spring.
Q How do I control an attack?
A On young plants, nip out damaged shoots as soon as they are seen. With older plants you can wait until normal clipping time. A second clip in late summer should remove most of the eggs. All clippings should be burned or binned, or put in a large-scale composting system, not your own compost heap.
Q Are there any suitable sprays?
A Products recommended for aphids should also help control psyllids if used in spring when the nymphs are feeding.