Lacebugs are sap sucking true bugs in the family Tingidae. About 20 species occur in Britain. They are named after the lace like appearance of the wings. Find out more about British species from British bugs 

Pieris lacebug is a small (3-4mm long) with wings marked with a black and white lace-like pattern. It can be responsible for causing pale mottling most notably on the leaves of Pieris and Rhododendron. Rhododendron can also be host to the Rhododendron lacebug Stephanitis rhododendri, however since its arrival in Britain pieris lacebug has become the most frequently found. 

Look out for the following symptoms of pieris lacebug on Pieris and Rhododendron;

• The foliage develops a coarse pale mottling on the upper surface and by late summer the leaves can have a bleached whitish yellow appearance
• Heavy feeding damage may cause leaf drop on Pieris
• The underside of affected leaves is discoloured with brown excrement spots
• Adults, nymphs and cast skins may be seen on the lower leaf surface
• The adults are black insects, 3mm long, with wings that are held flat over the insect’s body. The wings are transparent with a broad black X-shaped marking
• The nymphs are wingless and have spiny blackish brown bodies

Note that rhododendrons can also be damaged by the rhododendron lacebug, Stephanitis rhododendri. This causes similar damage but is much less common than pieris lacebug and is not found on Pieris. Rhododendron lacebug has wings that are only faintly marked with a darker line across the wings near the base.

Check Pieris and rhododendrons frequently from spring onwards so action can be taken before a damaging opulation has developed. When choosing management options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section and avoiding pesticides. Within pesticides the shorter persistence products (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. Pesticide treatments are likely to kill natural enemies and are only likely to be successful if the entire plant can be reached. 

Non-pesticide control

• Where possible tolerate populations of pieris lacebug
• Encourage predators and other natural enemies of suckers, in the garden, such as birds, ladybirds, wasps and ground beetles.

Pesticide control

• Organic sprays, such as natural pyrethrum (e.g. Bug Clear Ultra 2, Neudorff Bug Free Bug and Larvae Killer) or plant oils (e.g. Vitax Plant Guard Pest & Disease Control, Bug Clear Fruit & Veg, Vitax Rose Guard) can give good control of lacebugs. These pesticides have a very short persistence and so may require reapplication to keep lacebug numbers in check.  Plant oil and fatty acid products are less likely to affect larger insects
• Plant invigorators combine nutrients to stimulate plant growth with surfactants or fatty acids that have a physical mode of action against lacebugs (e.g. Ecofective Bug Control, Growing Success Bug Stop, Rose Clear 3 in 1 Action SB Plant Invigorator and Westland Resolva Natural Power Bug & Mildew). These products contain some synthetic ingredients and so 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)
• A systemic containing the active ingredient Flupyradifurone (Provanto Smart Bug Killer) is available 
• The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) is also available

Download

Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Pieris lacebug overwinters as eggs that are inserted into the leaf veins but adult insects can persist on the foliage until mid-winter.

The eggs hatch in May and the nymphs initially cluster together on the underside of leaves. They later disperse and reach the adult stage by mid to late summer.

Rhododendron lacebug has a similar lifecycle.