Their offspring began emerging in early July, with our first picture on 3 July. I’ll leave the image file dates in place so you can reach your own conclusions:
We think a titmouse (a known predator) pecked some holes, including the upper hole on the middle tube, as they seemed to expose solid (and presumably inedible) chitin from the outside:
More holes appeared in a few days:
The irregular spacing along each tube suggests they don’t emerge in the reverse order of installation:
Three days later:
Two weeks after the first holes appeared:
No more holes have appeared since then, so it seems one young wasp emerges every few days.
This nest produced about a dozen wasps, with perhaps as many launch failures. We’ll (try to) remove it and examine the contents in a few months.
We expect they’ll start building nests all over the house in another month …
Update: Fortunately for us, no nests appeared before the first freeze, so the wasps are holed up elsewhere for the winter.