Harlequin bug organic control

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PHOTO: Lois Elling/Flickrby Grace Hensley July 21, 2014

When Susy Morris, who blogs and farms in Liberty, Maine, went out to her vegetable garden in early June, she spotted a few different kinds of beetles on her asparagus, cucumbers and potatoes, but the harlequin bugs that attacked her cabbages were making a holey mess of her garden.

Harlequin bugs (Murgantia histronica) are red or yellow and black hard-shelled bugs in the stink bug family. Found in warm southern states as early as the Civil War, harlequin bug territory can now reach as far north as the Great Lakes and New England. Fortunately, I’m blessed by the cool maritime climate in the Pacific Northwest and don’t encounter them—you can hate me if you want.

Adult harlequin bugs overwinter in old plants, then lay eggs in the spring. Looking like some kind of Mod furniture, the barrel-shaped striped egg cases are quite distinctive. These insect pests can reach adult stage in an alarmingly short 48 days, so when you find the eggs, be vigilant in destroying them. Ken-ichi Ueda/Flickr

Insect pests are often named for the host plant that they consume, so harlequin bugs ought to be named broccoli bug or cabbage bug. They feast on all members of the brassica family, including collards, kale and even related ornamental genuses, such as Cleome, Matthiola, Erysimum (wall flowers) and Alyssum. A bit like vampires, harlequin bugs pierce stems and leaves and suck out plant juices, so look for discolored spots around a hole in your leaves.

Unfortunately, these sap-sucking insects will also eat tomatoes, corn, beans, squash, okra and tree fruits, so take the time to inspect any plants that are wilting. Because males produce an attracting pheromone, the bugs tend to congregate in one place, so look for unusually stressed plants in otherwise healthy rows.

Below are twelve organic techniques that will keep your kale and broccoli free from harlequin bug destruction.

General Techniques

Standard pest-management strategies will help you deal with pests of all types, including harlequin bugs. Here are a few you should incorporate into your garden-maintenance plan.

1. Encourage Strong Plants

Pay attention to your crops’ water and soil needs. Water deeply to encourage strong, deep roots. Brassicas are heavy calcium feeders, so add ground oyster shells or eggshells when you plant. You might need to add dolomitic limestone make calcium more available to your plants. Soil tests are also important for new crop fields and will tell you how to better balance out your soil’s nutrients.

2. Weed and Clean

Promptly remove languishing plants from the garden and inspect them for pests. (If they are infested, throw them in the trash, not the compost.) In mid-summer and again in the fall, pick up leaf-litter and remove weedy habitat, where the adult harlequin bugs can overwinter.

3. Hand-Pick Bugs

Toss harlequin bugs in a bucket of soapy water; squishing them will emit a pungent odor. (They aren’t called stink bugs for nothing!) Be vigilant in this practice, especially in spring as the weather warms.

Physical Deterrents

If you have a large garden plot where hand-picking pests is unreasonable, barrier methods can be effective in keeping pests like harlequin bugs at bay.

4. Row Covers

Row covers, which are suspended above the crop on PVC piping or wire, work really well for plants, like cabbage, that don’t need pollination to produce—they can stay under their fleece from planting until harvest. Use a lightweight, pervious fabric, such as Reemay, and tuck in the fabric edges with stones or soil to prevent harlequin bugs and other pests from slipping in underneath.

5. Kaolin Clay

Typically used on fruit crops, this white silicate clay can be sprayed to prevent bugs from feeding and is easily washed off at harvest.

Organic Chemical Solutions

While pesticides—even organic ones—shouldn’t be the first pest-management solution you turn to, they can be used sparingly if you have an infestation or if your site is too large to manage by other means.

6. Insecticidal Soaps

An effective way to kill harlequin bugs is with a simple combination of a 1-percent insecticidal soap solution, which penetrates their hard shells, and neem (0.9 percent) or pyrethrin (0.012 percent). This combination is a contact-insecticide, so you’ll have to squirt the eggs, nymphs and adults directly. Apply insecticidal soaps in early morning, before the bugs are active, to maximize effectiveness. Do not use neonicotinoid insecticides, as there is increasing evidence that it is a widespread bee killer.

7. Home-Brewed Pesticides

Plant Chrysanthemum cinerariifolium (also known as Tanacetum cinerarifolium), a white daisy-like plant that will deter all pests naturally by attacking the nervous system of insects. Commercially available as pyrethrins, this chemical is derived from the seeds of this plant. Collect flower heads when they are in full bloom. Dry and grind them up. Soak 1 cup of powder in 1/2 gallon of very warm water for 3 hours. Add 1/2 cup of dish soap and use immediately. Repeat weekly as nymphs hatch.

Companion Plants and Polycultures

These age-old strategies might have been used by your grandma, but they’re reliable strategies that can be used for managing all kinds of pests.

8. Boundary Crop

Surround brassicas with strong-scented plants, such as chamomile, celery, basil, garlic, mint, rosemary and sage, to help mask their strong odors. You can even plant chrysanthemum, a natural pyrethrin producer.

9. Trap Crops

Grow an early crop of mustard, broccoli or kale to attract and trap pests. Harvest and discard this crop before your main crop is planted.

10. Polycultures/Intercropping

Instead of growing them as a boundary, inter-mix main crop with the plants listed in No. 8 to distract harlequin bugs.

Animal Help

Greatly reduce your workload by using predatory insects and animals that feast upon harlequin bugs to rid your garden of this pest.

11. Parasitoid Wasps

Effective against hard-shelled pests, tiny non-stinging hymenopteran wasps are tireless workers. You can order these wasps online or plant wildflowers and herbs with broad umbrella-like blooms, such as yarrow, caraway and fennel to encourage them into your garden. Don’t purchase braconid and trichogramman wasps for use against harlequin bugs, though—they prefer the soft-bodied aphids, cutworms, moths and caterpillars.

12. Guinea Fowl

Of all the methods mentioned, I like this solution from Morris best. She lets her small flock of guinea fowl free-range her garden during the day. Although slightly noisier than chickens, a small flock is a useful companion in the field, as they are much less destructive to leafy crops and don’t scratch up plants as aggressively as chickens.

Harlequin Bug – Vegetables

Back to Vegetable Crops

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

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.

Back to Top

Harlequin bug

Harlequin bugs are shield- shaped, have black-and-orange or black-and-red triangles on the back, and are about ¼-inch long. The harlequin bug is a type of stink bug; it releases a foul odor when disturbed.

Harlequin bugs–also called shield bugs–suck plant sap from cabbage-family crops and other vegetables.

Harlequin bugs overwinter in garden debris and weeds. The females lay 300 to 500 distinctive eggs in neat double rows on leaf undersides in spring. The eggs look like tiny white barrels with black hoops. Eggs hatch in a week and nymphs emerge.

Nymphs are red and black and oval and feed for a few weeks; they become adults in about 5 weeks. There are usually three or four generations annually. In very warm winter regions, breeding can go on all year.

Harlequin bugs are found largely in the southern half of the United States.

Feeding Habits and Damage: Harlequin bug adults and nymphs suck plant sap from leaves, flowers, buds, fruit, and seeds of cabbage family crops. Punctures made at feeding time can cause leaves to be blotchy and wilt; feeding causes scarring and dimpling on fruits. Seedlings attacked by harlequin bugs usually do not survive.

Organic Controls: Insecticidal soap for light infestations. As last resort, dust or spray with pyrethrum, rotenone, or sabadilla if the infestation is serious.

Organic Control Calendar: Here is what you can do seasonally to control harlequin bugs:

  • Before planting: Remove or mow weeds near garden. Attract native parasitic wasps and flies by planting small-flowered plants
  • At planting time: Plant resistant varieties. Early in the growing season, exclude harlequin bugs from target plants with floating row covers.
  • While crops develop: When plants bloom pull back row covers for pollinators or hand pollinate. Handpick and destroy adults when they first appear in spring. Lure harlequin bugs away from crops by placing cabbage leaves elsewhere in the garden; destroy the decoyed bugs. Use insecticidal soap on large infestations every 2 to 3 days for 2 weeks—spray plants from top to bottom. Pyrethrum spray and rotenone spray or dust will kill harlequin bugs but also beneficial insects.
  • After harvest: Clean the garden of all plant debris and weeds.

Natural Predators: English sparrows and mockingbirds eat harlequin bugs. Turtles also eat harlequin bugs.

Scientific Name: Murgantia histrionica, Family Pentatomidae

Organic Control of Harlequin Bugs

The harlequin bug (Murgantia histrionica), also known as calico bug, fire bug or harlequin cabbage bug is a black stinkbug that is particularly destructive to cabbage and related plants in tropical America as well as throughout most of North America, especially the warmer parts of United States.

Yellow marked harlequin bug.

Host Plants:

In addition to cabbage, harlequin bugs can be a major pest of broccoli, radishes, kale, collards, mustard, turnips, Brussels sprouts and cauliflower. They may also attack corn, tomatoes, okra, squash, asparagus and beans.

Damage:

Both adults and nymphs cause damage to stems, leaves, fruits and seeds. They use their piercing mouthparts to inflict damage and suck away plant sap. Damage on leaves and stem look like uneven discolored spots. Young plants if left unchecked, will wilt, turn brown and eventually die. Mature plants will have their growth stunted. Damage on fruits will appear as dark holes or white-yellowish spots.

Symptoms include cloudy areas around the point of extraction, browning and wilting plants, and slower plant growth.

Description:

Adult harlequin bugs are attractive shield-shaped shiny black insects with bright red, yellow or orange markings. They measure about 7-10 mm in length.

Harlequin bug eggs.

Eggs are light colored barrel-shaped, 1 mm long and are laid in clusters in the foliage. Eggs hatch in 5-14 days.

The nymph is oval and similar to adults in appearance and color but slightly smaller and lack wings. Nymphs mature into adults in 5-8 weeks.

Generally 1-3 generations depending on location with warmer places more likely to have more generations.

Organic Control and Prevention of Harlequin Bugs:

1. Grow resistant varieties: Some types of brassica plants are naturally resistant to Harlequin bugs. The following varieties are recommended:

Cabbage: Copenhagen Market 86, Headstart, Savoy Perfect Drumhead, Stein’s Flat Dutch, Early Jersey Wakefield.

Collards: Green Glaze.

Cauliflower: Early Snowball X, Snowball Y.

Radishes: Red Devil, White Icicle, Globemaster, Cherry Belle, Champion, Red Prince.

2. Cultural control: Destroy heavily weeded and bushy areas in and near your garden. Adult stink bugs prefer overwintering in such sites among legumes, blackberries, Russian thistle, mustards and little mallow. Till the growing area, destroy and rid of crop debris and good weed management will help minimize stink bug populations.

3. Monitor and handpick: Harlequin bugs have decent mobility so be prepared. They also release a stink gas when threatened so beware and cover your nose! Remove them and drop them into a bucket of soapy water. Shaking infested plant or tree will send them tumbling down. Growers have successfully controlled harlequin bugs by frequent vacuuming. Spray plants with water to knock them down and kill them off.

4. Plant trap crops: Mustard, millet, buckwheat, sorghum, sunflower, marigolds, lavender and chrysanthemums are good trap crops to attract stink bugs to attack them rather than your crop of interest. Once these trap crops are infested, keep a bag ready to trash the infested plant in.

5. Physical traps: Yellow sticky traps or bucket painted yellow filled with soapy water can rid of quite a few unsuspecting stink bugs. An open pipe painted yellow stuck into the ground can also be used effectively for trapping stink bugs. Then there are commercially available stink bug traps that can be tried out.

6. Beneficial insects include ants, ladybird beetles, minute pirate bugs and some lacewings, all of which destroy stink bug egg masses. Attract these insects by planting several nectar producing flowers. Praying mantises, toads and some birds (including chickens and ducks) would love to feed on some adult Harlequin bugs.

7. Sprinkle diatomaceous earth in your garden and in prone areas. It works by breaking down the waxy protective layer on the stink bugs exoskeleton, eventually causing it to dehydrate.

8. Make a garlic spray and use as frequently as needed. Stink bugs detest the potent smell of garlic and will repel them from your garden.

9. Kaolin, a soft, white silicate clay mineral can be combined with water to form a protective physical powdery barrier that will prevent stink bugs and other pests from feeding on plant tissue.

10. Use an organic insecticidal soap and spray this solution directly on stink bugs or in areas they frequent. The soap kills the bugs by breaking down their protective exterior and dehydrating them.

11. Neem oil is another natural product that can help reduce stink bug populations by disrupting their feeding and mating habits.

12. Companion planting: Plant garlic, tansy, mint, catnip and radish to help repel Harlequin bugs.

Harlequin Bug Facts & Control

Harlequins are found throughout the continental United States and reach southward through Mexico to its native countries in Central America. It can be found in agricultural fields as well as home gardens.

In both the adult and nymph stages, this insect drains the juices from leaves and stalks with its sharp needle-shaped mouth.

So… What are Harlequin Bugs?

The adult Harlequin bug, a shield-shaped bug with bright red, orange, and black markings, is generally about 3/8″-1/2″ in length.

Nymphs look similar to the adults, but they are more roundish in shape and do not have wings.

Eggs are barrel-like in shape and are light yellow or gray. The eggs are deposited in clusters on the leaves of crucifers.

Reproduction Patterns of Harlequin Bugs

Harlequin bugs spend the winter hidden under plant debris, then, after emerging in the spring, females will lay their eggs. Eggs are laid in two-row clusters on the underneath parts of leaves. When she has finished, the female will have laid about 150 eggs. The female will fiercely defend her eggs from predators.

Within three weeks, the eggs will hatch and the emerging nymphs will begin feeding on the host plant. Nymphs feed for about two months and progress through five instars until they become adults. There are anywhere from 1 to 4 generations per year depending on the climate of a particular region.

Harlequin Bug’s Habitat

Harlequins are found throughout the continental United States and reach southward through Mexico to its native countries in Central America. It can be found in agricultural fields as well as home gardens.

Its favorite foods include members of the cabbage family, including Brussel sprouts, broccoli, cauliflower, and kale. It also feasts on members of the mustard family, including wild mustard, peppergrass and watercress.

In a pinch, these injurious pests will also partake of corn, tomatoes, squash, asparagus and beans.

Symptoms of Harlequin Bug Damage

Harlequin bugs in both the adult and nymph stages drain the juices from leaves and stalks with its sharp needle-shaped mouth.

Symptoms of harlequin bug infestations include cloudy areas around the point of extraction, browning and wilting plants, and slower plant growth.

Results of a Harlequin Bug Infestation

Damage from an infestation of harlequin bugs includes stunted plant growth, wilting plants and dying plants.

Although older plants can withstand an attack better than younger plantings, the older plants may show slowed growth. Younger plants may be damaged so severely, they may end up dying.

Natural & Organic Controls

What?

The combination of Insecticidal Soap and Botanical Pyrethrins will kill harlequin bugs on contact if they are spotted on your plants.

How?

Insecticidal Soap (Potassium Salts of Fatty Acids) & Pyrethrin – combined are the organic equivalent of a one-two knockdown punch. The soap will penetrate the insect’s shell enough to weaken and dehydrate the insect and allow the pyrethrin to absorb into the insect and do its job.

Pyrethrin is a powerful nerve agent and will paralyze and kill the insect on contact. Keep in mind this soap is not like dish detergent, it’s a base from a blend of natural plant sources and pyrethrin oils and comes from the chrysanthemum flower. An effective and organic combination…

When?

Use Insect Soap & Pyrethrin as a contact killer. Use in accordance with directions on the product label.

Safer® Brand offers a variety of harlequin bug control products to help control and eliminate this garden pest and revive your plants. Please check out our harlequin bug control products for more details about how they work and how, when, and where they should be applied.

If you are concerned about a plant or unsure of how it will react to these solutions, test an inconspicuous area and wait 24 hours before applying full coverage. As a general rule, much like watering, do not use any liquid insecticides in the peak of the day or when temperatures exceed 90°F.

Natural Predators

Parasitic wasps and parasitic flies may be able to help control harlequin bug infestations.

Parasitic wasps and flies attack the eggs, nymphs and adults, paralyzing the harlequin bugs and laying their eggs inside of them. When the eggs hatch, the offspring will feed on the harlequin bug eggs, larvae or adults. Attract them by growing flowering plants, especially those that produce nectar or pollen.

Parasitic wasps can be attracted through the flowering plants or purchased through commercial growers. Purchases should be done as soon as possible once harlequin bugs have been spotted.

Most local greenhouses and garden centers can help you determine the right planting time for nectar and pollen producing plants to ensure that the pollen and nectar will be available when the wasps arrive.

Environmental Controls

Remove or till under any plant debris left over from the harvest to get rid of harlequin bugs. Removal of bordering weeds and vegetation is also an important step in controlling a harlequin bug infestation.

Planting resistant varieties of crops is another method of helping to control problems caused by harlequin bugs.

Remove and discard plant debris. This will help prevent the adult harlequins from finding a place to overwinter. Overwintering adults can also be eliminated by tilling under any plant debris after the harvest.

Remove any weeds or vegetation along the perimeters of the field or garden, where the harlequin bugs may hide for the winter.

Resistant varieties of crops or plants can be purchased at your local garden center, from garden catalogs, or on the Internet.

Remove or till under any plant debris left over after harvesting. Remove any weeds or vegetation along the perimeters of the field or garden throughout the growing season and after the harvest.

Plant the resistant varieties according to the temperature and your climate zone. The professional staff at your local garden center can advise you on when to plant.

Safer® Brand leads the alternative lawn and garden products industry, offering many solutions that are compliant with organic gardening standards. Safer® Brand recognizes this growing demand by consumers and offers a wide variety of products for lawns, gardens, landscapes, flowers, houseplants, insects and more!

To Hell with Harlequins

Jane Edmanson

JANE EDMANSON: When these little black and orange critters appear, often overnight and in huge numbers, it can strike terror into the hearts of gardeners. They’re called harlequin bugs and they’re sap-sucking pests, much like aphids and thrip, and they attack the young, juicy new growth of many plants. So what can you do?

They’re particularly partial to plants in the hibiscus family, like the mallow weed. This is a common weed in southern states and it has a little purpley pink flower and they love to harbour in the leaves and they chew the flowers. So if you can get rid of the mallow weeds, you’re going a long way to reducing their numbers.

But if your garden is already infested, they’re easy to control. You just need to make a strong soapy mixture in a bucket, using washing up liquid and warm water. Use twice as much detergent as you would normally when you’re doing the dishes in the sink and about a third of the water. A quarter of a bucket is about right. Yeah, we got one or two in. They drop off the plants really easily when they’re disturbed, so just hold the bucket underneath and they’ll fall straight in.

The soap works by clogging up the breathing pores in their exoskeletons and they’ll suffocate in no time flat.

It’s that simple, and if you have plague proportions of harlequin bugs, just keep at it and you won’t have the problem in your garden for long.

common name: harlequin bug
scientific name: Murgantia histrionica (Hahn) (Insecta: Hemiptera: Pentatomidae)

The harlequin bug is an important insect pest of cabbage and related crops in the southern half of the United States. This pest has the ability to destroy the entire crop where it is not controlled. The harlequin bug injures the host plants by sucking the sap of the plants, causing the plants to wilt, brown and die.

Distribution (Back to Top)

The harlequin bug is a southern insect ranging from the Atlantic to the Pacific coasts. This insect is rarely found north of Colorado and Pennsylvania. It first spread over the southern United States from Mexico shortly after the Civil War.

Life Cycle and Description (Back to Top)

A generation of the harlequin bug requires 50 to 80 days. The life cycle consists of three stages: egg, nymph and adult. Harlequin bugs pass the winter as adults (commonly referred to as stink bugs) and true hibernation is doubtful.

Eggs: Eggs of the harlequin bug resemble tiny white kegs standing on end in a double row (Figure 1). Approximately 12 eggs are laid together in one batch, usually on the underside of the leaves of the host plant. Each egg is marked by two broad black hoops and a black spot. The eggs hatch in four to 29 days, the time varying with the temperature.

Figure 1. Eggs of the harlequin bug, Murgantia histrionica (Hahn). Photograph by James Castner, University of Florida.

Figure 2. Eggs and nymphs of the harlequin bug, Murgantia histrionica (Hahn). Photograph by Lyle Buss, University of Florida.

Nymphs: There are five or six nymphal instars that feed and grow for four to nine weeks before they are capable of mating. The head coloration of the nymphs ranges from pale orange (in first instar), darker (in second to fourth) to black (in fifth instar). Antennae of first instars are colorless and darken to black with each progressive molt. The thorax ranges from pale orange in first instars to a final pattern of scarlet, white, yellow and black in the fifth or sixth instars. The abdomen coloration progresses similarly to that of the thorax, getting showier with each progressive molt.

Figure 3. Nymph of the harlequin bug, Murgantia histrionica (Hahn). Photograph by James Castner, University of Florida.

Adults: The adults are gaudy red-and-black-spotted stink bugs about 9.5 mm long, with flat, shield-shaped bodies. At rest, the front pair of wings overlap and the insect’s back appears to be marked with a distinct X.

Figure 4. Adult harlequin bug, Murgantia histrionica (Hahn). Photograph by James Castner, University of Florida.

Hosts (Back to Top)

Plants commonly attacked by the harlequin bug include such crucifers as horseradish, cabbage, cauliflower, collards, mustard, Brussels sprouts, turnip, kohlrabi and radish. In the absence of these favorite hosts, tomato, potato, eggplant, okra, bean, asparagus, beet, weeds, fruit trees and field crops may be eaten.

Damage (Back to Top)

The harlequin bug feeds on its host plant by sucking the plant’s juices. The literal “sucking-to-death” of the host plant results in wilting, browning, and eventual death. Throughout most of its range, the harlequin bug continues to feed and reproduce during the entire year. Further north, the approaching winter drives the bugs into the shelter of cabbage stalks, bunches of grass, and other rubbish. Adults are usually the only stage to survive winter conditions. During the first few warm days of spring, the adults emerge by the time the earliest garden plants are set out.

Figure 5. Feeding injury by harlequin bug, Murgantia histrionica (Hahn). Photograph by James Castner, University of Florida.

Management (Back to Top)

Cultural control. Hand-picking and destruction of the insect pests and egg masses may deter damage where low numbers of insects are found. Hand destruction of the adults in the fall and spring as they emerge from “hibernation” before they lay eggs is an effective control. This may be aided by the use of trap crops such as turnip, kale, or mustard in very early spring or late in the fall after the main crop has been harvested. Once the pests have concentrated in these areas, they can be killed by applying insecticides or by covering the trap crop with straw and burning. Trap crops should never be used unless they can be given careful attention to destroy the bugs attracted to them.

Selected References (Back to Top)

  • Anonymous. (Unknown). Key to bugs. Insect and Related Pests of Flowers and Foliage Plants. (17 August 2012).
  • Ghidiu GM. 1988. Harlequin bug. FS-Cooperative Extension Service. Rutgers University, NJ. (246) 20. ill.
  • Miller MC. 1971. Regulation of populations of the harlequin bug, Murgantia histrionica, by egg parasites. Journal of the Georgia Entomological Society 6: 255-257.
  • Paddock FB. 1918. Studies on the harlequin bug. Experiment Station, TX. Texas Agricultural Experiment Station Bulletin 227.
  • Smith JB. 1897. The harlequin cabbage bug and the melon plant louse. Experiment Station, NJ. New Jersey Agricultural Experiment Station Bulletin 121.
  • Sullivan MJ, Brett HC. 1974. Resistance of commercial crucifers to the harlequin bug in the coastal plain of North Carolina. Journal of Economic Entomology 67: 262-264.
  • Thomas WA. 1915. The cabbage harlequin or calico bug. South Carolina Agricultural Experiment Station Bulletin 28.

How to Manage Pests

Harlequin bug—Murgantia histrionica

Harlequin bugs are attractive shield-shaped insects in the stink bug family and are usually black with bright red, yellow, or orange markings. Adult bugs are 3/8 inch long.

Identification

Harlequin bugs can be confused with Bagrada bugs, an invasive species, but are much larger and lack the white markings characteristic of Bagrada bugs. Harlequin bugs may also be confused with stink bugs. Coloration in bugs varies. The consperse stink bug, Euschistus conspersus, is usually gray brown to green with speckled black legs. Don’t confuse the consperse stink bug with the rough stink bug, Brochymena sulcata, which is a predator. The brown marmorated stink bug, often confused with the rough stink bug or consperse stink bug, is an invasive species and serious pest of many fruit and fruiting vegetable crops. Two other common species are the Say stink bug, Chlorochroa sayi, and the southern green stink bug, Nezara viridula. The Say stink bug is green with a white rim around its borders. The southern green stink bug is bright green and larger than other stink bugs.

Life cycle

Drum-shaped eggs with circular “lids” are laid in clusters on foliage. The nymphs, nearly round and often brightly colored, remain close together at first but scatter as they grow. They pass through four or five molts, gradually developing wings and adult coloration. Adults overwinter on the ground under leaves and become active in March or April. Stink bug infestations originate when adults fly in from weedy areas, often from the edges of sloughs and creeks where blackberries grow. Damage is often limited to the edges of fields near these areas, but in years with a lot of spring rain and late weed growth, stink bugs may be numerous and damage more widespread.

Damage

Harlequin bugs suck fluids from plant tissue. They leave yellow or white blotches on areas of leaves where they have been feeding; heavy infestations can cause plants to wilt, turn brown, and die.

Solutions

Handpick bugs or their eggs. Eliminate groundcovers or weedy areas (especially mustards) in early spring before populations build up. Destroy old cole crop plants and mustards because they provide breeding areas. Insecticides are generally not recommended in gardens for stink bugs. Parasites and general predators may contribute to control.

By Gene McAvoy|June 1, 2012

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Identification

This pest can destroy an entire crop when it is not controlled. The harlequin bug injures the host plants by sucking the sap of the plants. The bug literally “sucks-to-death” the host plant resulting in wilting, browning, and eventual death.
The adults are gaudy red-and-black-spotted stink bugs about 3/8 inch
long, flat, and shield-shaped. At rest, the front pair of wings overlap and the insect’s back appears to be marked with a distinct “X.”

Survival And Spread

Throughout most of its range, the harlequin bug feeds and reproduces during the entire year. In cooler areas, winter weather drives the bugs into the shelter of crop debris and other rubbish.
Harlequin bugs pass the winter as adults and true hibernation is doubtful. During the first few warm days of spring the adults emerge by the time the earliest transplants are set out.

A generation of the harlequin bug requires 50 to 80 days. The life cycle consists of three stages: egg, nymph, and adult.
The eggs of the harlequin bug resemble tiny white kegs standing on end. Approximately 12 are laid together in a double row, usually on the underside of the leaves of the host plant. Each egg is marked by two broad black “hoops” and a black spot. The eggs hatch in from four to 29 days, depending on the temperature.

There are five or six nymphal instars that feed and grow for four to nine weeks before they are capable of mating and laying eggs. The head coloration of the nymphs ranges from pale orange in the first instar, becoming darker, and finally black in the last instar. The thorax ranges from pale orange in first instars to a final pattern of scarlet, white, yellow, and black in the fifth or sixth instars. The abdomen coloration progresses similarly to that of the thorax, getting more colorful with each progressive molt.

Management Methods

Destruction of the adults in the fall and spring as they emerge from “hibernation” before they lay eggs is an effective control. This may be aided by the use of trap crops of turnip, kale, or mustard in the very early spring or late in the fall after the main crop has been harvested.

Once the pests have concentrated in these areas, they can be killed by applying insecticides or by covering the trap crop with straw and burning. Trap crops should not be employed unless they can be given careful attention to destroy the bugs attracted to them.
Harlequin bugs may be controlled with insecticides applied to the foliage.

Consult UF/IFAS recommendations for currently labeled insecticides for harlequin bug control in Florida vegetables.

Gene McAvoy is the Associate Director of Stakeholder Relations for the UF/IFAS Southwest Florida Research and Education Center in Immokalee, FL. See all author stories here.

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