On Crops: Broccoli, cabbage, kale, and occasionally other vegetables.
Brightly marked black-and-orange shield bugs found on cabbage family crops in summer are usually harlequin bugs. Young harlequin bugs are often black and yellow. They tend to congregate and mate on summer kale or collards. About one-third inch long, harlequin cabbage bugs are sometimes called calico bugs. They have black legs and short, segmented antennae.
Harlequin bugs suck plant juices, robbing them of moisture and leaving behind feeding wounds. Overwintering as adults, harlequin bugs may be active year round win very warm climates.
The flower called cleome can be used as a trap crop for harlequin bugs; they are also drawn to mustards.
Hand pick as many as you can, and use spinosad (a biological pesticide) if problems are severe. Scout for lines of barrel-shaped eggs attached to leaf undersides and destroy them.
In warm climates, grow early brassicas and harvest them promptly, before harlequin bugs become numerous. Use row covers to protect seedlings planted in summer for fall harvest.