Harlequin Bug - Vegetables

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Orange and black bug on broccoli, cauliflower, and kale

Harlequin bug (Murgantia histrionica) 
Photo: Dr. Mike Raupp

This pest is most often found on cabbage family members (broccoli, cauliflower, collards, kale, horseradish, etc.) It is very partial to cleome, an annual flower. It is a true bug (has a triangular shaped thorax) and sucks leaf sap leaving small white spots known as stipples. Leaves wilt and turn brown from prolonged feeding. 

Appearance

• Eggs: Tiny white barrels encircled by black bands with a black crescent on top. Laid in small clusters arranged in rows of six on leaf undersides.
• Nymphs: Rounded and black, with pale green markings which soon turn brilliant red and yellow. Five instars (growth stages between two periods of molting in the development of a nymph).
• Adults: Shield-shaped body, up to 3/8" long, brightly colored, typically black and yellow or black and red— color patterns vary with the season.

Egg cases

Newly hatching eggs

Life Cycle/Habits

• Adults overwinter in sheltered locations in or near gardens, including winter crops and organic debris.
• In spring, adults emerge and deposit eggs on leaf undersides.
• Nymphs and adults feed by piercing leaves to suck nutrients.
• Harlequins are a stink bug and adults will produce a smelly odor when disturbed.
• They love the annual flower, cleome.
• Two or three generations occur per year.

Host Plants

• Cole crops (a.k.a. crucifers or brassicas) such as cabbage, broccoli, cauliflower, turnip, collards, horseradish, arugula.
• Many other crops may be affected, including asparagus, bean, cantaloupe, onion, pea, potato, squash, and tomato, as well as fruits such as grape, peach, pear, and raspberry.

Signs/Symptoms

• White spots, known as stipples, result from the piercing-sucking feeding of nymphs and adults.
• Leaves brown and look tattered.
• Plants may wilt, be deformed, or, under severe infestation, die.

Stippling damage caused by harlequin bugs

Monitoring

• Turn leaves over to spy egg clutches.
• Watch leaves for white or yellow blotches, distortion, and browning.
• The bright colors of nymphs and adults makes them easy to spot, though they will hide under leaves when threatened.

Prevention/Control

• Clean up garden at season's end. Remove all crop debris to eliminate overwintering sites.
• Search out and manually crush eggs, nymphs, and adults.
• Use floating row cover to exclude this pest.
• Spray nymphs with insecticidal soap alone or in combination with pyrethrum or use neem oil.
• Cleome can be grown as a trap crop. Spray infested cleome with an insecticide or pull plants up and dispose of in black trash bags.
• Check catalogs for resistant varieties of many cruciferous plants.

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