Oak lace bug
An insect pest which attacks oaks, the oak lace bug can reduce growth and weaken trees. With number of other diseases already affecting oaks, the arrival of the oak lace bug would pose a serious threat.
Common name: oak lace bug
Scientific name: Corythucha arcuata
What does it affect?: oaks and sometimes maples
Areas affected so far: not currently in the UK
Origin: North America
What does oak lace bug damage look like?
- Spots of colour loss (chlorosis) on the upper surface of the leaves appear as the pest feeds on sap within the oak.
- Spots of chlorosis join together into large yellow and bronze patches as populations increase.
- Leaf drop can occur with heavy infestations.
- Droplets of liquid frass (waste material) deposited by the bug on the undersides of the leaves as it feeds. These dry into hard black spots.
What is the oak lace bug?
The oak lace bug is a non-native species of lace bug. We do have native lace bugs, but none of them feed on oak trees. The adult bug is very easily recognised as it has very delicate milky-white and lacy wings with variable brown markings. They reach up to 4mm long. They feed on oak leaves during the summer months. There are multiple generations in a season so adults, nymphs and eggs can all be present on leaves throughout late spring and summer. The adults overwinter in leaf litter and crevices in bark.
Credit: Doug Wechsler / Nature Picture Library
How did the oak lace bug get here and what impact will it have?
While this pest is yet to reach the UK, there is a risk of it arriving on infested plants or plant materials. If they do arrive, they will spread locally to new hosts as adults fly and are blown by the wind. As this pest affects leaves, it impacts the photosynthesis of the tree. This makes infested trees more vulnerable to other pests and diseases. Consecutive years of severe oak lace bug damage, combined with other stress factors, might even kill some trees. Any damage will be most severe during dry weather, when trees are already under stress.
What are we doing about it?
To combat the spread of pests and diseases like the oak lace bug we have:
- Developed a UK and Ireland Sourced and Grown assurance scheme to make sure that all the trees we plant and sell are produced in the UK. This reduces the risk of importing new pests and diseases that could add stress to our native oaks.
- Lobbied the government to improve biosecurity at border points to stop new pests and diseases entering the UK.
- Partnered with Observatree, a tree health citizen science project which trains volunteers to spot pests and diseases, thereby helping tree health authorities identify and manage outbreaks early.