Found my first Scarlet Tiger caterpillar this afternoon, curled up as I was weeding. I usually see them about this time of year on warm days on stems of plants that aren't their foodplant, usually a couple of feet up. I've found them in the past on rose suckers, pear suckers, and rosemary. I assume they are sunning themselves? I've seen them go up and then shortly after they descend.
This one was smaller than I usually see them - whether it's because they are smaller this year or if it's only the bigger ones that climb up I don't know.
As far as I can tell they are feeding on Herb Bennett, Geum urbanum - I've found them in several places over the years and that was more or less the only thing growing there. Previously I've found them on nettle and another time I think one was feeding on forget-me-not which seems to have now died out in the garden.