Bugs on a plane: Volunteers hunt for invasive insect pest on famous trees

Volunteers are on the hunt for hitch-hiking bugs which pose a threat to the plane trees that line streets and parks in London and other cities.

The Woodland Trust said a team of “Observatree” volunteers have been called in to support official survey activities to track the appearance of the plane lace bug, native to North America and now widespread in Europe.

The move comes after the first sighting of the bug in the UK in 18 years, which was reported by a member of the public and traced back by the Forestry Commission to an outbreak on trees in central London.

Volunteers are scouring the area and reporting any other sightings across the UK to chart the spread of the insect, using binoculars to look for the yellow discolouration focused on leaf veins which the bugs cause.

The plane lace bug (C Malumphy, Fera/PA)
A plane lace bug (C Malumphy/Fera/PA)

Woodland Trust experts warn the discovery of the bug is “a serious concern” because of its ability to get about and the damage it does to plane trees by sucking their sap.

The bugs are attracted to weakened trees, likely to be found in London where they are stressed by other environmental factors, the trust said.

The tiny insects can weaken trees, making them susceptible to other pests and diseases, even causing death in combination with fungal infections in severe cases.

The Woodland Trust also said that in large numbers they can be a nuisance, landing on people in parks, getting into homes, and have occasionally been reported to bite people, which can cause a mild rash.

Investigations are continuing into how the plane lace bug arrived in the UK but the Woodland Trust said it is known for being a great hitch-hiker, and could spread quickly as it has in other European countries.

The London plane, a cross between an American sycamore and Oriental plane, is the capital’s most common tree, and is a popular choice for city planting because it is tough and resistant to pollution.

Vicky Bolton, a citizen science officer who leads the Observatree volunteers at the Woodland Trust, said: “The discovery of the plane lace bug is a concern due to its ability to get around and the damage it does to plane trees by sucking their sap.

“It is a very small invertebrate that is great at hitch-hiking on vehicles, clothing or bags, and the density of planes in London means this pest may spread quickly, as seen in other European countries.

“Adult lace bugs can fly, but they could also drop on to cars and move this way – having so many plane-lined streets in many urban areas creates the perfect opportunity. ”

And she warned: “The bugs are more attracted to weakened trees – especially likely in areas such as London, with street trees that may be stressed by other environmental factors.

“The heat island effect also means they may be capable of growing their populations faster.

“They can weaken trees and in very severe cases cause death in combination with fungal pathogens, so they are a serious concern.”

Plane lace bug leaf damage showing discolouration of much of the leaf
Damage to a leaf caused by a plane lace bug (C Malumphy/Fera/PA)

Members of the public are also being encouraged to keep a lookout for signs of the plane lace bug and report suspected findings.

Andrea Deol, of the Forestry Commission, said: “Volunteers from Observatree, a multi-partnership project set up by Forest Research, play an important role in protecting the nation’s woodlands from pests and diseases through surveillance.

“Following recent findings in central London of plane lace bug, we are conducting further surveillance and ask members of the public to help by reporting suspected plane lace bug findings via our online portal TreeAlert.”

– To report suspected sightings, people can visit: https://treealert.forestresearch.gov.uk/