Harlequin Bug Life Cycle: An Intriguing Journey Revealed

The harlequin bug, scientifically known as Murgantia histrionica, is a common pest affecting many vegetables. They can be found throughout the Southern United States, ranging from the Atlantic to the Pacific coasts. These bugs are known for their striking orange, black, red, and yellow patterns, which make them an attractive yet destructive presence in gardens.

The life cycle of the harlequin bug consists of three stages: egg, nymph, and adult. Adult harlequin bugs overwinter in sheltered locations near gardens, including winter crops and organic debris. In spring, they emerge and deposit their eggs on the undersides of leaves, which usually hatch within a week.

Harlequin bugs cause damage to plants by piercing leaves and sucking out their nutrients. This affects the growth and overall health of vegetables such as broccoli, cabbage, and kale, leading to a decline in crop yields. Gardeners should be aware of the signs of harlequin bug damage and take action to prevent or mitigate these harmful pests from invading their gardens.

Harlequin Bug Life Cycle

Egg Stage

  • The harlequin bug, Murgantia histrionica, lays barrel-shaped eggs.
  • Easily identified by black bands and a black circle or crescent on top.

Nymph Stage

  • Nymphs have five instars.
  • Grow and molt through each instar stage to eventually become adults.

Adult Stage

  • Vivid red, orange or yellow markings on a black body.
  • Shield-shaped, oval appearance, 1/4 to 3/8 inch long.

The life cycle of the harlequin bug, which spans 50 to 80 days, can be divided into three major stages – the egg stage, nymph stage, and adult stage. During each stage, the bug undergoes various physical transformations, ultimately maturing into a reproductive adult.

Egg Stage: A mature female lays clusters of barrel-shaped eggs. These egg clusters typically have a distinctive appearance, with two black bands encircling pale eggs, and a black circle or crescent on the top.

Nymph Stage: Once hatched, the nymphs go through a series of five instars. In each instar, the nymphs grow, molt and eventually develop into fully grown adults.

Adult Stage : The adults have shield-shaped or oval bodies with vivid red, orange or yellow markings on a black background. They measure around 1/4 to 3/8 inch long. These adults overwinter in sheltered locations close to gardens, emerging in the spring to deposit eggs on the undersides of leaves.

During their life cycle, harlequin bugs can attack various vegetable crops, affecting plants such as broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, kohlrabi, mustard, radish, and turnips.

A comparison of the different life stages of the harlequin bug can be seen below:

Life Stage Primary Characteristics Duration
Egg Stage Barrel-shaped, pale with black bands Days to weeks
Nymph Stage Five instars, gradual growth Until adult molt
Adult Stage Vivid markings, shield-shaped body Completion of life cycle

Identification and Physical Characteristics

Color and Patterns

The Harlequin bug has a distinct color pattern that includes:

  • Primary colors: orange, black, red, and yellow
  • Secondary color: green

The vivid colors form patterns across their body, with a predominantly red and black appearance. Their wings exhibit an intricate design as well.

Size and Shape

The Harlequin bug is shield-shaped, giving it a unique appearance. Here are some key features related to its size and shape:

  • Length: 1/4 to 3/8 inch long
  • Shape: Oval from the top view

Comparison of Harlequin Bugs and Similar Insects

Comparing Harlequin bugs to other similar-looking insects can help in proper identification:

Features Harlequin Bug Similar Insect
Color Red, black, orange, and yellow patterns May have different color patterns
Shape Shield-shaped/Oval from the top view May exhibit varied shapes
Size 1/4 to 3/8 inch long Length may differ

Harlequin bugs also lay barrel-shaped eggs with a black circle or crescent shape on the top and a tiny black spot between the side bands. The eggs are pale with two black bands, which further distinguishes them from other insects.

Host Plants and Habitat

Preferred Host Plants

The harlequin bug (Murgantia histrionica) mainly targets plants in the Brassicaceae family, also known as the mustard family or crucifers1. Some commonly attacked plants include:

  • Cabbage
  • Kale
  • Broccoli
  • Cauliflower
  • Radish
  • Mustard
  • Brussels sprouts
  • Collards
  • Kohlrabi
  • Turnips
  • Horseradish

In addition to crucifers, the harlequin bug is a secondary pest of various fruit and vegetable crops, such as:

  • Beans
  • Peas
  • Tomatoes
  • Pears
  • Raspberries
  • Onions
  • Cantaloupes
  • Squash
  • Asparagus
  • Okra2

Geographical Distribution

Harlequin bugs are native to Central America, Mexico, and the southwestern United States3. They have since become a significant pest in other regions, including the East Coast and Midwest areas of the United States. The harlequin bug’s distribution is influenced by temperature, as they cannot survive in freezing conditions. As a result, their presence is more prevalent in warmer climates.

Damage and Economic Impact

Crop Damage

Harlequin bugs can cause remarkable damage to various crops, especially those belonging to the Brassicaceae family. These pests can impact both the yield and quality of the crops they infest. Some host plants frequently affected by harlequin bugs include:

  • Beans
  • Tomatoes
  • Cabbage
  • Broccoli
  • Greens

Harlequin bugs can be identified by their distinctive orange or red and black patterns. Damage occurs when these pests pierce plant tissues and suck the nutrients, resulting in small white spots on the leaves.

Effects on Vegetable Crops

Below are some examples of the impact harlequin bugs have on specific vegetable crops:

  • Beans: Infestation leads to discolored and deformed pods.
  • Tomatoes: Affected plants show yellowing leaves and reduced fruit development.
  • Cabbage and Broccoli: Severe infestations cause plants to wilt and leaves to become distorted.

Comparison:

Crop Damage Symptoms
Beans Discolored and deformed pods
Tomatoes Yellowing leaves, reduced fruit development
Cabbage Wilting, distorted leaves
Broccoli Wilting, distorted leaves

By damaging multiple crops, harlequin bugs have a significant economic impact, causing reduced yield and the potential loss of considerable revenue for farmers and growers. It is crucial to implement effective pest management practices to minimize the damage caused by these pests.

Prevention and Management

Cultural Practices

  • Keep fields clean: remove weeds and plant debris that might serve as a habitat for harlequin bugs
  • Plant trap crops: like mustard greens to attract harlequin bugs away from main crops
  • Rotate crops: change crops annually to reduce harlequin bug populations

Insecticides and Chemical Control

  • Apply insecticides: use registered products for harlequin bug control
  • Follow label instructions: ensure proper dosage and application method
  • Monitor resistance: pay attention to the effectiveness of chemicals over time

Pros and Cons of Insecticides

Pros Cons
Effective Potential resistance
Fast-acting Possible harm to non-target organisms
Widely available Environmental concerns

Biological Control

  • Encourage natural predators: such as the harlequin bug’s parasitic wasps help in keeping their population in check
  • Avoid broad-spectrum insecticides: these may kill beneficial insects along with pests
  • Introduce released predators: like predatory bugs and parasitic wasps, obtained from commercial sources

Examples of Biological Control Agents

  • Predatory bugs: e.g., assassin bugs, damsel bugs
  • Parasitic wasps: e.g., Trichopoda pennipes (tachinid fly), other parasitoids of harlequin bug

Additional Information

Entomologist Insights

Harlequin bugs, or Murgantia histrionica, are considered part of the stink bug family. They have a unique life cycle, which consists of three stages: eggs, nymphs, and adults1. Adults can be found in various shades of brown and white, which help them blend into their environment. These bugs are predominantly found in North America, stretching from the Atlantic to the Pacific coasts, with a significant presence in the southern United States and Mexico2.

Their main choice of habitat includes vegetables and weeds, which can be affected by this pest. For example:

  • Vegetables: cabbage, mustard, turnips
  • Weeds: grape, beet, ucer, potato3

Entomologists have observed that harlequin bugs have a preference for plants in the family Brassicae, including mustards4. They are also known to be secondary pests to other fruit and vegetable crops. For pest management, experts suggest inspecting for both adult bugs and their eggs.

Resources for Pest Control

There are several insecticides and methods available for controlling harlequin bug infestations, such as:

  • Insecticidal soap: A safe and effective way to eliminate nymphs5.
  • Spinosad: A biological insecticide derived from naturally occurring bacteria6.
  • Chemical insecticides: Acetamiprid, carbaryl, cyfluthrin, and gamma-cyhalothrin7.

Insecticides should always be applied as per the label instructions. It’s important to consult resources such as UC IPM’s “How to Manage Pests” or an experienced entomologist for guidance on the most appropriate pest control method for specific situations.

Pros and Cons of Pest Control Methods

Method Pros Cons
Insecticidal Soap Safe for the environment and non-target organisms Must be applied directly on the bugs
Spinosad Organic and highly effective Can be harmful to certain beneficial insects
Chemical Insecticides Fast-acting and can provide quick results Can impact non-target insects and have environmental implications8

Using a combination of different pest control methods, along with proactive measures like regular inspection and plant care, can help effectively manage harlequin bug infestations.

Footnotes

  1. New Mexico State University 2
  2. Texas A&M University 2
  3. West Virginia University 2
  4. https://extensionentomology.tamu.edu/insects/harlequin-bug/
  5. https://www.colostate.edu/harlequin-bug
  6. https://www.ipm.ucanr.edu.exclude/
  7. https://entomology.ucdavis.edu.exclude/
  8. https://www.lsuagcenter.com/

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

    View all posts
  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

    View all posts

19 thoughts on “Harlequin Bug Life Cycle: An Intriguing Journey Revealed”

  1. I have spent the last few hours finding out what these beautiful little creatures are and this page has been by far the most informative. I like keeping weird animals that no one else would even consider as a pet, over the last summer I got looper caterpillars to change into moths. I have 2 immature male Tectocoris diophthalmus that I found today. Any information on how to keep them, I’m new to this but I think I’m trying to say I want to know how to keep the 2 males I found today and I’m also interested in how to find their eggs and keep them through all the stages of development. I have lived in the Illawarra for most of my life and loved these bugs since was very young, I’ve heard there is a photo of me covered in them, when I was about 2.

    Reply
  2. I have these bugs in my garden, they destroyed my tomato plants and now are attacking my mandarin tree. Does anyone if there is a pest control that I can buy to stop these pests from destroying my fruit trees. I live in Melbourne
    Thanks

    Reply
    • I also am in Melbourne and have them every spring to summer. I’ve managed to keep them at bay by spraying them with soapy (earth dishwashing detergent).
      Also if you kill one and leave it others come to its rescue. So leaving them where you kill them will help lure others.

      Reply
  3. I have these bugs in my garden, they destroyed my tomato plants and now are attacking my mandarin tree. Does anyone if there is a pest control that I can buy to stop these pests from destroying my fruit trees. I live in Melbourne
    Thanks

    Reply
  4. They are harlequin bugs and are a destructive pest. They are sap suckers and any plant or fruit they have fed from will either die or fruit will be covered in hard scars that make it inedible. Females lay around 30 eggs and the young look like little red dots that only change to full colour in their final moult. It takes no time before there are thousands of them in your garden. I have been fighting them for many years and found they really cannot be eradicated, just controlled. I make a mixture in a one litre sprayer of 12 cup cheap vinegar, fill sprayer with warm water and a good squirt of cheap dish detergent. This is a contact spray so make sure they are wet with this solution. Some of them will run around for a while but it does kill them. It is harmless to both plants and pets and is also good for other garden pests, particularly white fly.

    Reply
    • Have just found these little pests on my newly planted healthy bouganvilleau . Thank you for your insight. To save my garden I will remove it from its pot and hope the bugs don’t transfer to my disease free garden.

      Reply
    • Thank you for your information. I have a plague like infestation and they are attacking my lavender and succulents.
      Is your solution harmful to bees?

      Reply
  5. They are harlequin bugs and are a destructive pest. They are sap suckers and any plant or fruit they have fed from will either die or fruit will be covered in hard scars that make it inedible. Females lay around 30 eggs and the young look like little red dots that only change to full colour in their final moult. It takes no time before there are thousands of them in your garden. I have been fighting them for many years and found they really cannot be eradicated, just controlled. I make a mixture in a one litre sprayer of 12 cup cheap vinegar, fill sprayer with warm water and a good squirt of cheap dish detergent. This is a contact spray so make sure they are wet with this solution. Some of them will run around for a while but it does kill them. It is harmless to both plants and pets and is also good for other garden pests, particularly white fly.

    Reply
    • Thank you for your information. I have a plague like infestation and they are attacking my lavender and succulents.
      Is your solution harmful to bees?

      Reply
  6. I had these the first year I moved into my current house 4 years ago (in Melbourne). I mistook the babies for baby ladybirds, so didn’t kill them – bad move. They ended up in plague proportions. They are sap suckers and will kill your garden. I did lots of research at the time regarding management, and couldn’t find much. From memory, they like to lay their eggs in a particular weed, so I made sure that the garden was really well weeded to break the cycle. Also, I could find no natural predators (birds aren’t interested in them). I set about manually squashing them at every opportunity (they are very skittish and run like a race horse when they see you & hide, which is really frustrating). I did read of a lady who had captured a lot of them, then made a tea out of the dead bodies and sprayed that on them, with good effect. I never got that far as they died out at the start of winter. Since then I have had the occasional one, which I squash, but I think making sure their egg laying weeds are removed is the best way to control them. My preferred method for weed and bad insect management is boiling water. If I ever see another cluster of babies, I will tip boiling water in them – doubt they will survive that.

    Reply
    • Lol run like a racehorse, that they do. We have quite a few this year also. We have a hibiscus and I keep it trimmed so I can go out there daily and catch the little buggers. I have a small container which I put some water in and put under them on the plant. Then when they try to get away from me, they drop in the container or I tap the plant and shake them into it. I the. Squash what I have found but I will try adding some dishwasher liquid for added annihilation of the little beasts.

      Reply
  7. We live on the Mornington Peninsula, Victoria and they have all but destroyed hollyhocks, a few amongst ground cover violets and possibly in a young callistimon where one in three bushes was savagely eaten.
    I used pyrethrum spray to send them on their way.

    Reply
  8. @Kath ward – I tried your mix (which for the addition of the vinegar was the only main variation I had found from another recipe or two I’ve already tried – which didn’t work.. (a strong detergent / water mix only) – this one with the vinegar added works a charm – has really knocked them for 6 – so will keep at it to keep them at bay.. thanks for posting this!

    Reply
  9. ‘@Kath ward – I tried your mix (which for the addition of the vinegar was the only main variation I had found from another recipe or two I’ve already tried – which didn’t work.. (a strong detergent / water mix only) – this one with the vinegar added works a charm – has really knocked them for 6 – so will keep at it to keep them at bay.. thanks for posting this!

    Reply
  10. I have thousands of them and they have ruined my tomatoes for 2 years running. Spraying with soapy water does seem to work on the ones that you spray, many more escape. Can anybody tell me the name of the weed?

    Reply
  11. From Albury. Have found them on the trunk of a ten year old Brachychiton trilobus that has just thrown seed for the first time.
    Not on B. acerifolius, nor B.populneus or B.rupestris

    Reply

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