August 4th. I took a slight short detour from my usual route to look at an unusual mushroom by the trail. After satisfying my curiosity, I walk a little further along the trail to meet the main trail I wanted.
That explained something else. I parked at the lot uphill from this section of trail. While I was gathering my gear, a couple of Southern Yellowjackets (Vespula squamosa) flew in through the open door of the car. They seemed more active than I’m used to seeing. I just stood back and they flew off within a few minutes.
Postscript. The trail was still blocked on August 11th and I encountered a couple more yellow jackets in the car. Guess the trail will be closed now until winter at the earliest. The major nest building will occur this month, and will reach its maximum size in October to December. Hopefully this will be an annual nest and the trail will be opened again in winter or spring.
Wikipedia: Vespula squamosa