Common name: emerald ash borer
Scientific name: Agrilus planipennis
What does it affect?: ash trees
Areas affected so far: not yet present in the UK
Origin: East Asia
The emerald ash borer has killed billions of ash trees in the US. If it gets here, it will do the same to our already vulnerable ash populations.
Common name: emerald ash borer
Scientific name: Agrilus planipennis
What does it affect?: ash trees
Areas affected so far: not yet present in the UK
Origin: East Asia
Symptoms include:
Emerald ash borers are long, slender, metallic green beetles which grow between 7.5mm and 13.5mm long.
The adult females produce between 60 and 90 eggs which they lay singly or in small clusters into bark crevices. They hatch in seven to 10 days.
When the eggs hatch the larvae burrow into the bark and begin feeding on the tissues that transport water and nutrients through the tree just under the bark. As they feed, they grow larger, between 26 and 32mm long, causing extensive damage to the tree.
The larvae feed voraciously until temperatures begin to fall in the autumn. When winter comes, they overwinter in tree bark or outer wood. They emerge as adults from May and start the cycle again.
Eventually, successive generations of larvae kill the tree as the water and nutrient transport systems become blocked.
Emerald ash borer is native to eastern Asia and has been spreading westwards at a rate of 40km per year. In 2019 it was first reported in Europe in Ukraine. It has also had an impact on huge areas of the US and Canada.
Credit: David Cappaert / Michigan State University
The emerald ash borer is yet to reach the UK, but the biggest risk of introduction comes from imported wood, particularly firewood. This was the case in the US where campers often carry firewood from one area to another, speeding up the spread of the pest.
If the pest were to arrive in the UK, it would have a devastating ecological impact. Our ash trees are already under threat from ash dieback, so the introduction of the emerald ash borer could even make ash trees locally extinct in some areas.
To combat pests and diseases like the emerald ash borer we have:
We are fighting back against pests and diseases. Find out what we're doing to prevent the spread and protect the UK’s trees.
More pests and diseases: