Hi all!
Well, the following two insects,
common Shiny Blue Beetle, and
common Tiger Dragonfly
do not appear, ever, at all, period, when there are 15 empty pots, which leads me to believe that they require a special plant or foliage to be present for them to appear.
i would guess the common Tiger Dragonfly requires a Tigerfern but I do not have any proof of this. not being a common shiny blue beetle myself, i do not have any guesses as to what flower or foliage a common shiny blue beetle would find appealing.

so Deathwing - your work so far on this project has been exemplary, but your job is not 100% done as you may have thought.. you have two more to go

I'm "rooting" for you

Cheers,
-Borg