Cotton crops face numerous challenges involving pests, one of which is the cotton harlequin bug. This colorful and destructive insect thrives on vegetation, causing damage to various plants, particularly those from the Brassicaceae family, such as broccoli, cauliflower, cabbage, and kale 1. Other plants that may be targeted by harlequin bugs include mustards, radish, and even some fruit and vegetable crops like beans, tomatoes, and onions 2.
These shield-shaped or oval bugs suck the fluids from plant tissues, leaving small white spots on the leaves, and eventually, affecting the overall health of the plant 3. Being aware of the presence and impact of cotton harlequin bugs in your garden or farm is crucial for timely and effective pest management.
Cotton Harlequin Bug Overview
Appearance and Identification
The Cotton Harlequin Bug (Tectocoris diophthalmus) is a vibrant jewel bug, known for its striking colors. Some key features include:
- A mix of red, orange, blue, black, and metallic green shades
- Oval-shaped body
- Distinctive markings
These bugs are typically found on the so-called cotton plant, but their bright colors make them easily recognizable.
Distribution and Habitat
The Cotton Harlequin Bug can be found in various regions, such as:
- Eastern Australia
- New Guinea
- Pacific Islands
These bugs prefer a habitat that includes cotton plants, although they can be found on other host plants in their native range.
In conclusion, the Cotton Harlequin Bug is a unique and visually striking insect with a diverse habitat spanning multiple regions. Its captivating appearance makes it easily identifiable and an interesting subject for study.
Life Cycle and Behavior
Eggs
The life cycle of cotton harlequin bugs begins with their egg stage. Female bugs lay clusters of drum-shaped eggs on leaves. These eggs have circular “lids” which show their unique appearance.
Nymphs
Harlequin bug nymphs undergo a process called incomplete metamorphosis. They go through five instars as they develop.
- First instar nymphs are small and reddish-orange.
- Nymphs become larger and darker in color with each molt.
Adults
Males and females show some differences in appearance:
- Males: Brighter colors and smaller in size
- Females: Duller colors and larger in size
Adult harlequin bugs feed on plant sap, which can cause damage to crops such as cruciferous vegetables.
Comparison of Nymphs and Adults:
| Feature | Nymphs | Adults |
|---|---|---|
| Size | Smaller | Larger |
| Color | Reddish-orange (Instars vary) | Brighter in males, duller in females |
| Metamorphosis | Incomplete (Five instars) | Not applicable |
As cotton harlequin bugs move through their life cycle:
- Eggs hatch into nymphs
- Nymphs go through five instars
- They reach full adulthood and can reproduce
Host Plants and Feeding Damage
Impact on Agricultural Crops
Harlequin bugs, or Murgantia histrionica, primarily affect plants in the Brassicaceae family, which includes vegetables such as:
- Cabbage
- Broccoli
- Cauliflower
- Mustard
- Radish
These pests are also known to cause damage to other crops like:
- Beans
- Greens
- Tomatoes
Feeding on the sap of these plants, they may cause wilting, browning, and eventual death1. Their presence can be particularly detrimental in the southern United States due to favorable conditions for their population growth2.
Effects on Ornamental Plants and Gardens
In addition to agricultural crops, harlequin bugs can have a negative impact on ornamental plants and gardens, including the Malvaceae family, which is home to plants such as:
- Cotton
- Hibiscus
- Illawarra flame tree3
Harlequin bugs usually feed on stems, young shoots, and flower buds, which can lead to:
- Stunted growth
- Deformed flowers
- Reduced seed production
In cotton plants specifically, they may cause cotton bolls to drop prematurely, leading to reduced yield4.
| Crop / Plant Family | Impact / Damage |
|---|---|
| Brassicaceae (veggies) | Wilting, browning, death, reduced fruit/vegetable production1 |
| Malvaceae | Stunted growth, deformed flowers, reduced seed production, boll drop3 4 |
Overall, cotton harlequin bugs can cause significant damage to both agricultural crops and ornamental plants. Effectively managing these garden pests can help mitigate their effects and protect the health of your crops and garden.
Pest Management Strategies
Cultural Control Methods
Cultural control methods help prevent and reduce harlequin bug infestations. These methods include:
- Crop rotation: Changing crops from season to season disrupts the harlequin bug life cycle.
- Clean up: Removing crop residues and organic debris prevents bugs from hiding and reproducing.
- Trap crops: Yellow mustard or horseradish attract harlequin bugs, drawing them away from the main crop.
Biological Control Agents
Several natural predators and parasites help control harlequin bugs. Examples include:
- Predatory insects: Lady beetles, lacewings, and predaceous stink bugs prey on harlequin bugs.
- Parasitic wasps: These insects lay eggs inside harlequin bug eggs, killing them.
Chemical Control Options
Several chemical options combat harlequin bug infestations:
- Insecticidal soap: A soapy water solution helps control small infestations.
- Pyrethrin: A natural insecticide derived from chrysanthemum flowers. Use as directed on the label.
Comparison table:
| Method | Pros | Cons |
|---|---|---|
| Cultural control | Non-toxic, easy to implement, sustainable | Limited effectiveness in large farms |
| Biological agents | Natural, minimal harm to beneficial insects & environment | Can be slow to control infestations |
| Chemical control | Quick results, effective against larger infestations | May harm non-target organisms |
Remember that proper management involves monitoring, timely action, and selecting appropriate strategies. Consult your local extension office for tailored advice on managing harlequin bugs in your region.
Bug Control Recommendation Tool
Relationship to Other Bugs
Comparison to Stink Bugs
Cotton harlequin bugs, or Murgantia histrionica, belong to the Hemiptera order, which also includes stink bugs and leaf-footed bugs1. These true bugs share some common traits:
- Both have piercing-sucking mouthparts used for feeding on plant sap
- They often emit unpleasant odors when disturbed or crushed
- Their bodies are generally shield-shaped or oval
However, there are noticeable differences between them:
| Feature | Harlequin Bug | Stink Bug |
|---|---|---|
| Size | 1/4 to 3/8 inch long2 | Up to 3/4 inch long |
| Color and markings | Robust and black, with vivid red, orange, or yellow markings2 | Generally brown or green, with fewer markings |
| Preferred host plants | Vegetables in the Brassicaceae family3 | Various crops, fruits, and ornamental plants |
Notable Similar Species
The hibiscus harlequin bug is a close relative of the cotton harlequin bug. Both insects share similar characteristics:
- Shield-shaped or oval bodies
- Distinct, vibrant colorations
- Found mainly on plants within specific plant families
However, the hibiscus harlequin bug is specific to certain hibiscus species and other members of the Malvaceae family, whereas the cotton harlequin bug attacks vegetables in the Brassicaceae family3.
In summary, while cotton harlequin bugs share similarities with stink bugs and other Hemiptera species, they have unique characteristics that set them apart.
Footnotes
6 Comments. Leave new
Is this bug toxic and does it do any harm to human? Can you pick it up by your hands?
To the best of our knowledge, the Cotton Harlequin Bug is not toxic and it does not pose any risk to humans or pets.
Out of curiosity, I did an image search of the picture provided in this posting and found its source: http://dawnstetzel.blogspot.com.au/ (the 48th image on the latest post). It seems likely that the blog’s author is not the same person as the poster here.
Thanks for that information. We will gladly remove the image if the copyright owner instructs us to remove it.
We have these in our kindy, they hang around 1 particular tree & seem to eat out of the large seed pods, (not sure what the tree is called), have been looking for a name for them as the children call them stink bugs, & i know their not. Everywhere i have found on the net so far that has these bugs is down south but we are in queensland, just thought i would share with you!
I got mine yesterday from my garden in Timor Leste. Just love dit and thought it was amazing. So I wanted to know who I had got. And I came here to your website.