Anyway, the Dark Glassy Tigers were congregating on the Crotalaria retusa (common name: Rattleweed; Family: Fabaceae / Leguminosae) despite the very badly attacked plants. In fact, they can be seen perching on the seed pods and piercing their proboscis through holes in the pods to feed on some toxic chemical compounds pyrrolizidine alkaloid and use it for their defense against predation.
Such an effect is similarly noticed on the plant Artemisia scoparia.
A link on the Crotalaria is attached herein for reference: