I had Harlequin Bugs on my broccoli in the back yard. I’d never seen those before. They weren’t on all the plants, just the ones that didn’t look like they were doing well. Were they stressed before or after the bugs paid a visit? I’ll say they were stressed before the bugs. I cut them down and threw the infested ones in the trash, not the compost.
The affected broccoli was planted densely with a chocolate cherry tomato volunteer struggling to share the same space. Lesson? Thin the seedlings! Don’t leave unsuccessful plantings in the garden all summer.