Harlequin bugs are major pests of cruciferous and even other crop plants. Here’s how to control harlequin bugs and stop them from destroying your plants.
Harlequin bugs are common garden pets that prefer to feed on cruciferous plants such as vegetables in the Brassica family.
This includes cabbage, broccoli, mustards, and radish, to name a few.
These tiny bugs can be identified with their orange/ red and black patterned bodies. They can quickly wreak havoc if they find their way to your garden.
In this article, I will mention how you can control harlequin bugs and protect your precious greens.
Control Techniques
The Murgantia histrionica, i.e., harlequin bugs, are insect pests widespread in the southern and central parts of the United States.
They are also identified as broccoli or cabbage bugs, named after their host plants.
Harlequin bug eggs are laid in large batches and can quickly multiply their populations.
The adult harlequin bug population finds shelter among organic mush, such as plant debris and the underside of leaves.
However, worry not. There are some control techniques that you can use to manage these potential pest attacks.
You can opt for generic techniques, chemical treatments, or physical solutions. You can also choose to use other plants or animals to help.
Let’s take a look at these ways in detail.
Generic Techniques
The best way to keep pests away from your crop is to make your crop strong enough to be susceptible to pest attack.
You can do this by being careful with your plant’s soil and water needs.
Watering deeply to promote strong roots, running soil tests on potential new planting sites, and giving your plant the required nutrition will ensure it grows strong.
For instance, the plants of the Brassica family thrive on heavy calcium.
To keep the harlequin bugs away, make plenty of calcium available to your plant through eggshells, oyster shells and solutions, and other calcium supplements.
Maintain your plants by weeding them out regularly and checking for bugs or pests if you spot a handful of harlequin bugs, hand pick and toss them into garbage bins.
Chemical Treatments
The second major technique you can use to weed out your pests is chemical treatment.
Pyrethrin is an effective chemical to treat a harlequin bug infestation.
The chemical is derived from the seeds of the plant Chrysanthemum cinerariifolium.
This white daisy-like plant attacks the insects’ nervous system to incapacitate them.
You can use pyrethrin in an insecticidal soap solution with neem.
Sprinkling this solution directly on the eggs, nymphs, and even harlequin bugs in the adult stage early in the morning will ensure maximum results.
You can also make an organic pyrethrin pesticide at home. Dry and grind the flower heads of the fully bloomed Chrysanthemum cinerariifolium.
Add the powder to warm water and leave it for three hours. Follow by adding some dish soap and using the soapy water solution on the nymphs immediately.
You can repeat this process weekly on the newly hatching nymphs for the best results.
Polycultures & companion plants
Another effective technique to keep harlequin bugs away is to use companion plants for your main plant and intercropping.
Create a boundary of strong-odored plants like mint, rosemary, garlic, chamomile, or even chrysanthemum.
These plants will overpower the smell of your brassica plants and protect them.
Or you can grow them in a mix with your main plant to confuse and divert the harlequin bugs.
You can also use trap crops.
In this method, you attract and trap the pests by growing an initial batch of plants or crops and then discarding them. You can then plant your main batch.
Physical Solutions
Some individuals have also seen success using physical barriers such as row covers.
These work best for plants that don’t require pollination, such as cabbage.
You can also use white silicate clay spray on your plants to deter pests.
Predators
Beneficial insects like hymenopteran wasps and guinea fowls are great helpers in attacking harlequin bugs and other pests.
If you’re concerned about parasitic wasps, they are tiny and do not sting, which makes them perfect garden dwellers.
On the other hand, unlike chickens, the guinea fowl do not destroy plants and vegetation, making them an ideal flock to have.
Frequently Asked Questions
Are harlequin bugs harmful to garden?
Harlequin bugs can be very harmful to garden flowers, vegetables, and fruits.
They suck the sap from plants, and their feeding damage sometimes goes unnoticed until plants are weakened or stunted.
Insecticides can be effective in controlling problem harlequin bug populations, but a better approach is to remove weeds.
These are a major food source for harlequin bugs and provide barriers such as mulching and dusting these areas with diatomaceous earth, which acts as a natural barrier between the harlequin bugs and their food sources.
Are harlequin bugs harmful to humans?
Harlequin bugs are not considered to be harmful to humans, as they feed mostly on plants, fruits, and vegetables.
However, these bugs can become a nuisance when they gather in large clusters. Large swarms of these bugs may cause allergies or skin irritation if touched.
In addition, the presence of the bug can contaminate the product that is being harvested from gardens or farms.
While harlequin bugs are not directly hazardous to human health, their presence could cause problems for farmers and gardeners who need to make sure that their crops are pest-free before the sale.
What is the lifespan of a harlequin bug?
The lifespan of a harlequin bug is roughly two years, with larvae emerging in the spring and first adults seen in late summer.
It typically overwinters as an egg on grasses, roses, or other low vegetation. The female adults lay their eggs in masses that are yellow or white when first laid but turn brownish-black as they mature.
The developing nymphs will molt five times before becoming adults. They feed on various plants, including crucifers such as radishes, cabbage, and mustard.
What eats the harlequin bug?
The harlequin bug is eaten by a variety of predators, including spiders, ants, frogs, birds, and beetles.
They will also be eaten by beneficial predator insects such as ladybugs and hoverflies.
In order to more effectively protect itself from these predators, the harlequin bug has evolved the ability to produce chemical defenses that are rather foul-smelling.
Many times a predator will pick up the scent of this defensive secretion before they ever get close enough to consume the harlequin bug.
Wrap Up
Harlequin bugs are common garden pests in Central America that usually feed on cruciferous plants such as wild mustard, cabbage, broccoli, etc.
They can often destroy the entire crop or garden if not controlled and managed.
Several ways, from generic management techniques to chemical treatments and even using companion plants and animals, can be employed to destroy these notorious pests.
Thank you for reading!
Reader Emails
The harlequin bug often gets confused for a beetle, because of its shape and size.
Go through some of the letters from our readers below to understand the various colors and shapes this bug can be found in.
Letter 1 – Harlequin Bug
Like others I have been searching to figure out what kind of beetles have been living in my garden all summer. They stay on one particular plant and have been there since July. I’m in SoCal if that helps.
Thanks in advance,
Richard
Hi Richard,
The flaw in your searching is that the Harlequin Bug, Murgantia histrionica, is not a beetle but a true bug. It can be found on cabbage, sweet alyssum and wild mustard among other plants.
Letter 2 – Harlequin Bug
Can’t find this bug’s info anywhere!
The attached photo shows the bug. He and his friends are located in a patch of flowers in our back yard. I believe they are eating the leaves. Let me know if you need more info on the location. Any help you can provide me in.
Hi there,
You have an immature Harlequin Bug, Murgantia histrionica. They have sucking mouthparts and are often pests on cultivated plants in the cabbage family as well as on Sweet Alyssum and wild mustard. They are colorful members of the stinkbug family Pentatomidae.
Letter 3 – Harlequin Bug
Hi Mr. Bug Man,
Here is a “nicer” picture of what looks like a harlequin cabbage bug on your web site. You are welcome to use this if you care to. This one has been relaxing outside my house in Northern New Mexico for a few days on a tall weed. I think it’s charming, but then I’m not a gardener!
Thanks for the image.
Letter 4 – Harlequin Bugs
I think that these may be Harlequin bugs? By the way, the photos on your site are marvelous – what lovely bugs! I snapped these on an unknown plant in the field behind our house; possibly a mustard plant of some kind. Have been practicing taking pictures of small things like flowers, and am proud of this bug photo.
Liana
Hi Liana,
Our site does have many marvelous photos, all of which have been contributed by mostly amateur photographers like you. Not only should you be proud of your photo, you should also be commended for taking the time to properly identify your Harlequin Bugs, Murgantia histrionica.
Letter 5 – Harlequin Bugs
Location: Point Mugu, Ventura County, California
April 15, 2011 12:08 am
Hello! Thanks for the great site. I have a question for you: I often go hiking in the hills around Los Angeles and I love taking photographs of plants and wildlife. I was intrigued by the clusters of orange and black beetles I found I found one day clumped on some sage plants off the side of the trail. All of the plants in that area were covered in these beetles- particularly the sages. I haven’t been able to identify them, but they remind me of beetles I used to hear people call ”Japanese beetles” as a kid- however, searching this term on google revealed a much different result. Any ideas of what these sage-loving beetles could be?
Signature: Sara
Hi Sara,
These are Harlequin Bugs, Murgantia histrionica, and we also commonly find them in the Los Angeles area, though in Elyria Canyon Park near our Mt. Washington offices, we notice them feeding on the introduced mustard. In the vegetable patch, they feed upon collard greens and other members of the cabbage family. We have never seen them feeding upon sage, so your excellent photo has us quite intrigued. Harlequin Bugs are Stink Bugs in the family Pentatomidae, and unlike Beetles which have chewing mouthparts, they have sucking mouthparts. True Bugs also have incomplete metamorphosis while beetles have complete metamorphosis. True Bugs are often confused with beetles.
Letter 6 – Remains of a Cotton Harlequin Bug from Australia
Location: Gold Coast, QLD, Australia
May 24, 2016 5:27 am
Dear Bugman,
I was meditating on the porch today when I noticed a small orange object. It turned out to be the (exoskeleton?) of a strange little creature. I had simply never seen anything that alien looking in the insect kingdom so I thought it definitely necessary to send in a photo.
I’m on the Gold Coast, QLD Australia and it’s Autumn here at the moment.
Thank you very much, appreciate the site immensely.
Signature: Christopher Royce
Dear Christoper,
We can’t tell by the remains what killed this Hibiscus Harlequin Bug or Cotton Harlequin Bug, Tectocoris diophthalmus, but we believe it was eaten by something. The Cotton Harlequin Bug is a highly variable species, and your remains, like this individual on Flicker, are mostly orange while other individuals have a preponderance of metallic blue-green markings. According to the Museum of Tropical Queensland: “The Hibiscus Harlequin Bug sucks sap from hibiscus plants, bottle trees and related species. Its main foodplant is the native Beach Hibiscus (Hibiscus tiliaceus). It is also a minor pest of cultivated cotton, a member of the hibiscus family Malvaceae, leading to its other common name, the Cotton Harlequin Bug.”
Thanks so much for getting back to me, you guys run an awesome service!
Letter 7 – Harlequin Bug
Location: Fairfax, Virginia: Accotink Trail
June 10, 2016 1:27 pm
Hi, I have searched your website, my field guide, but cannot come up with an ID. It looks a good deal like a Willow Leaf Beetle, but not quite unless it’s a different subspecies? Perhaps you can shed some light on this? Thanks!
Signature: Seth
Dear Seth,
This is not a Beetle. It is a Harlequin Bug, Murgantia histrionica. Harlequin Bugs are Stink Bugs. According to BugGuide: “hosts: primarily Brassicaceae (horseradish, cabbage, cauliflower, collards, mustard, Brussels sprouts, turnip, kohlrabi, radish); may also attack tomato, potato, eggplant, okra, bean, asparagus, beet, weeds, fruit trees and field crops.”
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