Plane lace bug: what the agencies record

This page describes what the named sources say. It is not a diagnosis of any tree and does not say what should be done with one. Plane lace bug (Corythucha ciliata) is a small sap-feeding insect of plane trees. None of the three pages read lists it as regulated: Forest Research does not call it notifiable and welcomes records, and the Woodland Trust says it is not a regulated pest, so there is no requirement to take statutory action. Each section names its source, all read on October 8, 2026. The parent page, insect pests of trees, compares this insect with the other pests on the list.

Names

Forest Research gives the names plane lace bug, Platanus lace bug and sycamore lace bug, and the scientific name Corythucha ciliata. It adds a note on the last name: in North America trees of the genus Platanus are called sycamores, while in the United Kingdom sycamore means only Acer pseudoplatanus, so the insect does not attack what a United Kingdom reader calls sycamore. The Defra and Fera factsheet says the common name refers to the insect's host and to its lacy white outer skeleton. For the American tree itself see American sycamore.

Hosts

Forest Research lists the main hosts as London plane (Platanus x hispanica), oriental plane (Platanus orientalis) and American sycamore (Platanus occidentalis), and says other Platanus species have been reported. It lists several other plant genera from the literature, including Broussonetia papyrifera, Carya ovata, Chamaedaphne, Fraxinus and Quercus laurifolia, but says they are not considered main hosts and it is not clear that the insect can reproduce on them. The Defra and Fera factsheet says the insect feeds primarily on plane trees, often planted as city trees. The Woodland Trust describes London plane as the capital's most common tree.

What the sources say to look for

The Defra and Fera factsheet says adults are up to 4 mm long, can be hard to see on a leaf without magnification, and are found on the underside of leaves. It says this is the only lace bug in the United Kingdom that feeds on plane trees. The first sign of feeding it describes is stippling of small yellow spots on the upper leaf surface, often along the veins. As numbers rise the spots join into large yellow and bronze areas, and in a severe infestation whole leaves turn whitish and the tree may lose all its leaves in late summer. The factsheet adds that peeling bark in autumn, winter or early spring is one of the easiest ways to find overwintering adults. The Woodland Trust says its volunteers can pick the insect out from the ground with binoculars by looking for leaf discolouration.

Life cycle as the sources state it

Forest Research says that on the continent the insect makes two or three generations in a year. Females lay eggs on the underside of leaves, nymphs go through five stages, and a full cycle takes 30 to 40 days depending on temperature. It says adults and nymphs feed together in late summer, and that some of the last adults overwinter under loose bark, in leaf litter and in bark crevices. The Defra and Fera factsheet gives one to three generations a year and says a female can lay several hundred eggs, placed along leaf veins, during the warm months.

Where it is reported

Forest Research says the insect is native to North America and was first found in Europe in 1964 in Padova, Italy, reached at least nine other countries by 1986, and has since been introduced to Korea, China, Australia, Japan and Turkey. The Defra and Fera factsheet says it is found in most of mainland Europe. For the United Kingdom, Forest Research reports a small population at one Bedfordshire nursery in 2006, likely linked to imported plants, and the Defra and Fera factsheet reports outbreaks at two Bedfordshire nurseries on plane trees imported from France and Italy. No further populations were found there afterwards. Forest Research says the insect was identified on street and park trees in central London in summer 2024, and the factsheet says the Forestry Commission confirmed it there in September 2024. Forest Research lists it as present with distribution unknown though likely to be limited. The Woodland Trust says the 2024 London find was the first sighting since the 2006 find and was reported by a member of the public.

Spread

Forest Research says adults spread locally by flying or being blown to new host trees, and that vehicles, clothing and bags can carry them over longer distances. It says human activity is thought to be the main cause of long-distance spread and that there is little that can be done to stop the movement. The Woodland Trust makes the same hitchhiking point and says the density of plane trees in London could let the insect spread quickly, as it has in other European countries. It also says stressed street trees are more attractive to the insect. The Defra and Fera factsheet says the insect has been recorded biting people in Paris, Piedmont and Bucharest, in hot weather where adult numbers are high. The Woodland Trust says the bite can cause a mild rash or dermatitis.

What the sources say it does to trees

Forest Research and the factsheet agree that in most years the visible effect is bronzed foliage and early leaf drop. They say that after many consecutive years of heavy feeding trees may be weakened and more open to fungi and disease, and that repeated severe damage combined with drought may kill a tree. The Woodland Trust says that in very severe cases, together with fungal pathogens, it can cause death.

Regulated status and reporting

The Defra and Fera factsheet gives the status as present, not widely distributed and not under official control. Statutory action was judged inappropriate after the 2006 findings because the insect was thought to be established already. Forest Research and the factsheet name TreeAlert as the route for finds in the wider environment in Great Britain, and the factsheet names TreeCheck for Northern Ireland. For the offices in each country see the guide to reporting a pest in the United Kingdom.

Management as the sources list it

The factsheet says routine insecticide use on mature plane trees would be impractical because of cost, application difficulty and non-target effects, that approved insecticides could be used at nurseries, and that soap, hosing off and natural enemies such as assassin bugs, lacewings, spiders and predatory mites can lower numbers where needed. It says raising public awareness helps find the insect at low numbers. This page gives no product names, rates or timings. For who may apply pesticides, see pesticide licences.

Contains public sector information published by Forest Research and licensed under the Open Government Licence v3.0.