Harlequin Bug

What it does

Harlequin bugs feed in groups on cole crops, piercing leaves and stems to suck sap and injecting saliva that leaves white or yellow blotches and causes wilting. Their bright coloring warns predators that they taste bad. They are most active in warm weather and can quickly build up on cabbage-family plants.

Where it lives

They live in vegetable gardens and farm fields on brassica crops and related weeds such as wild mustard. Primarily a southern pest, they cannot survive hard winters in the far north; where winters are mild, adults shelter in plant debris and garden trash and become active again as temperatures rise.

How it breeds

Females lay distinctive eggs that look like tiny white barrels ringed with black bands, standing in neat double rows on leaves. Nymphs hatch and feed in clusters, maturing through several stages. In warm southern regions there can be three or more generations per year, overlapping through the season.

What it eats

Harlequin bugs feed on the sap of cole crops such as cabbage, kale, collards, broccoli, cauliflower, mustard, and radish, along with related wild mustard-family plants.

Identification

Adults are about 8-11 mm, shield-shaped stink bugs boldly marked in black with red, orange, and yellow, making them easy to recognize. The barrel-shaped black-and-white striped eggs and the similarly colored, rounded nymphs are also distinctive and unlike most other garden pests.

Signs of an infestation

• White or yellow stippling and blotches on cabbage-family leaves
• Wilting or stunted cole crops during warm weather
• Barrel-shaped black-and-white eggs standing in rows on leaves
• Brightly colored black, red, and orange bugs clustered on plants

Prevention tips

• Remove and destroy crop residue and mustard-family weeds that harbor them
• Handpick adults, nymphs, and egg rows into soapy water
• Use trap crops of mustard to concentrate bugs for removal
• Cover young plants with row covers and rotate brassica plantings

Professional solutions

This is a garden and farm pest, controlled mainly through sanitation, handpicking, trap crops, and treating young nymphs when populations are high. Removing overwintering debris and weeds reduces the next season's numbers. A local extension service can recommend region-appropriate options for protecting cole crops when infestations are heavy.