Harlequin Bug

Murgantia histrionica

Insectalso: Harlequin cabbage bug, Calico bug

A flashy red-and-black stink bug that is a major pest of cabbage-family crops, especially in warm regions. Both the adults and nymphs suck sap from the leaves, leaving blotched, wilted, and yellowed foliage that can kill young plants outright.

🔎 How to spot it

Adults are shield-shaped stink bugs about three-eighths of an inch, boldly patterned in shiny black and red-orange, unmistakable on a cabbage leaf. The eggs are a giveaway: they look like tiny white barrels banded with two black hoops, laid standing in double rows on the leaf undersides. Nymphs are rounder versions of the adult in the same red-and-black colors.

🥀 Damage it causes

Using piercing-sucking mouthparts, harlequin bugs drain sap from leaves and stems, leaving pale blotches, wilting, browning, and distortion; heavy feeding can wilt and kill young brassica plants. They attack cabbage, broccoli, kale, collards, radish, mustard, and related crops, and are worst in hot weather.

🛡️ Prevent it

Clean up and destroy old cole-crop plants and weedy mustards at season end and in early spring, since these shelter and breed the bugs before your crop is up. Protect plantings with row cover, and use a trap crop of mustard or an early brassica to draw the bugs away from the main crop, then destroy it with the bugs on it.

🧯 If it is already here

Handpick the adults and nymphs into soapy water and crush the barrel-shaped egg rows on the leaf undersides; persistent picking controls small plantings. Remove and destroy heavily infested plants. Insecticidal soap helps against nymphs, but the tough adults shrug off most sprays, so the egg-crushing and trap-cropping matter more.

💡 Good to know

The black-and-white striped, barrel-shaped eggs standing in neat rows are the easiest early warning; scout the undersides and rub them out before they hatch. Harlequin bug overwinters as adults in garden debris, so fall and spring cleanup of brassica trash and wild mustards is the foundation of control.