![Gall on the leaf stem of horse chestnut](/media/4244/oriental-chestnut-gall-wasp-istock-1155058314-cristian-storto-fotografia.jpg?center=0.62745098039215685,0.67180616740088106&mode=crop&heightratio=0.5622047244094488188976377953&width=647&rnd=132072232400000000)
Credit: iStock.com / Cristian Storto Fotografia
How did oriental chestnut gall wasp get here and what impact will it have?
These wasps spread through flight; they likely got to the UK through plant imports and spread locally.
On its own, the wasp is a low-impact pest. However, in high numbers the galls can weaken the host tree and make them more vulnerable to the other pests and diseases, particularly sweet chestnut blight.