I was up in the deforested heath looking at willows for signs of bud-break and spotted this caterpillar on a bush. Turns out it's the Northern Eggar - Lasiocampa quercus f. callunae. Specimen about 3 cm. long:
This is an interesting species (or species complex). The southern populations feed on Oak and have a one-year lifecycle. Northern and western populations feed on heather and willow and have a two-year lifecycle. Populations in the English midlands vary between one year and two year cycles.
I did find a few willows in bud-break:
And also a single specimen of Alder:
And with catkins:
One of the groups I'll be studying closely this year is leaf-miners. I've previously tended to be a bit cavalier in my leaf-miner hunting, but this year I'm going to be more organised, with target species and timescales all planned in advance.