Many of these were found on the upper inflorescence branches of Artemisia tridentata
, which is the host plant of Trirhabda pilosa
...to which these keyed in Hogue(1)
. This is subspecies vitatta
(the median pale-yellowish vittae extend from base to apex on each elytron, tapering apically).
Note how the Trirhabda
are resting facing downward near the apical branch tips. I think this is a common behavior for pre-mating female Trirhabda
of many species, who wait in this position for potential mates to approach from below.