Not my usual kind of post, but here is a photo from Newton Wood showing two oak trees standing side by side. The one on the left looks as it should in mid-June: full canopy, dense green. The one on the right, though, is barely clothed—just a sparse fringe of leaves at the crown, the rest stripped to bare filigree.
This is not an isolated case. Many oaks here, along with hazel, are showing similar damage. Leaves are full of holes and ragged edges—clear signs of caterpillar feeding. Yet there are no caterpillars in sight, which likely means they have finished feeding and are now pupating. Judging by the scale, there must have been an infestation. One can imagine the local tits and other insectivorous birds feasting well.
After some time spent consulting the digital oracles, I have narrowed the suspects down to three: the Oak Leaf Roller Moth (Tortrix viridana), the Winter Moth (Operophtera brumata), or the Oak Processionary Moth (Thaumetopoea processionea).
The first two are native to Britain and have a reputation for large-scale oak defoliation. Their larvae hatch in spring, feed voraciously, and are done by late May. The Oak Leaf Roller Moth is particularly known for folding leaves into tubes for cover, which might explain the crumpled shapes I saw on some of the lower branches.
The Oak Processionary Moth is a new arrival, originally from Central Europe. It was first noted in London in 2006 and remains mostly confined to the south of England. That makes it an unlikely suspect here in North Yorkshire.
Given all this, my money is on the Oak Leaf Roller Moth. Though, to be clear, I am no lepidopterist. Still, it is worth pointing out that despite the dramatic appearance, mature oaks will usually bounce back from such attacks and often grow a new flush of leaves by late June.
Leave a Reply