I hotglued the butterflies to a paper lantern, and for the wall installation used white poster putty. Unfortunately the project ground to a halt when I realized I need about twice the number of butterflies to get the effect I want, but had run out of paper, and had managed to empty the local stores' stocks. It'll take about a week to get the new shipments in, so for now, this is it:
I'd put up a few trial butterflies on the wall late last night, and when I woke up this morning, the 4-year-old had added a couple of spectators:
They are definitely staying up as part of this art installation.