Geographic location of the bug: Western Washington State
Time: 06:14 PM EDT
I found this in Kitsap County, a mile or two from salt water, walking along a boardwalk in a wetland surrounded mostly by grasses, red alders, poplars, willows, and a few conifers (Douglas fir, western red cedar, Sitka spruce, western hemlock), so I can’t associate it with any particular plant. There were also a few wild roses and snowberries around. I only found one caterpillar. Any idea what it might be?
How you want your letter signed: gardenjim
After a considerable internet search, we finally identified this Fingered Dagger Caterpillar, Acronicta dactylina. Fingered Dagger is a curious name, and BugGuide indicates: “from the Latin ‘dactylus’ (a finger); the origin of the common name but it is not clear how that name applies to this species.” According to BugGuide: “larvae feed on alder, birch, poplar, hawthorn, willow”, and you mentioned three of food plants listed in the vicinity of the sighting. BugGuide also states “uncommon, but widely distributed” and this BugGuide posting may indicate its range is expanding into areas that had previously been too cold, causing us to speculate “Global Warming?”