Four Lined Plant Bug: Quick Guide to the Garden Pest

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The Four Lined Plant Bug is a common garden pest found throughout much of the United States and Canada, specifically east of the Rocky Mountains. These insects, also known as Poecilocapsus lineatus, cause distinctive feeding damage on a wide range of plants, particularly those in the mint (Lamiaceae) and composite (Asteraceae) families.

Adult four-lined plant bugs are yellowish to yellowish-green in color and have four longitudinal black lines down their wing covers. Measuring about 1/2 inch long, they can sometimes be confused with striped cucumber beetles. The nymph stage of the insect is wingless and varies from bright yellow to red, with rows of black spots on its body.

These bugs feed on over 250 herbaceous plants, causing damage that initially appears as yellow stipples or spots. As the infestation worsens, the spots eventually turn brown to black, and in cases of large infestations, entire leaves may become brown. Although quick and difficult to detect, even a small number of four-lined plant bugs can cause noticeable damage to your garden plants.

Four Lined Plant Bug: Identification

Physical Appearance

The Four Lined Plant Bug (Poecilocapsus lineatus) is a small insect with a distinct appearance. The adults have:

  • A greenish-yellow body, about 1/4 inch long
  • Four black stripes running down the back
  • Black antennae
  • Yellow-green legs with black marks

Nymphs, or the younger stage of the bug, show slightly different features:

  • Bright red color when they first hatch
  • Black wing pads and black dots on their abdomen
  • As they grow, the color changes to reddish-orange
  • Wing pads become larger with a light-colored stripe on each1

Habitat

Four Lined Plant Bugs are native to the eastern and midwestern parts of the United States and Canada2. They inhabit a wide variety of plants – over 250 different types3. Commonly found on:

  • Herbaceous plants3
  • Flowers4
  • Vegetable gardens5

Here is a comparison between adults and nymphs:

Stage Body Color Stripes/Wing Pads Legs
Adult Greenish-yellow 4 black stripes Yellow-green
Nymph (new) Bright red Black wing pads Not applicable
Nymph (older) Reddish-orange Larger wing pads Not applicable

By learning to identify the Four Lined Plant Bug’s distinct physical traits and understanding their preferred habitat, gardeners and farmers can better detect and manage them, protecting their plants from potential damage.

Four Lined Plant Bug: Life Cycle

Eggs

  • Four Lined Plant Bug eggs hatch in late spring
  • Eggs are laid in vertical slits along plant stems

Four Lined Plant Bug eggs are banana-shaped and overwinter inside the plant stems. As the leaves on plants begin to emerge, the eggs hatch in late spring. Females lay these eggs in two to three-inch vertical slits along the plant’s stem1.

Nymphs

  • Reddish in color
  • Feed on upper side of leaves
  • Develop through five molts in 3-6 weeks

Nymphs are reddish and active, feeding on the upper side of leaves. In a period of three to six weeks, they undergo five molts, developing and growing more as they feed on new shoots2. Nymphs also have black spots and lack wing pads, making them easy to identify.

Adults

  • Yellowish-green with four black lines
  • Feed on plants and then mate
  • One generation per year

Adult four lined plant bugs are around 1/2 inch long and have a yellowish-green color, with four longitudinal black lines on their wing covers. After feeding for about a month, adults mate, thus completing their life cycle3. In general, there is only one generation of four lined plant bugs per year.

Host Plants and Damage

Affected Plants

The Fourlined Plant Bug is known to feed on numerous plant species, primarily including:

  • Herbaceous plants: such as mint, basil, and other herbs
  • Ornamentals: likegeranium, zinnia, and daisy
  • Shrubs and trees: forsythia, viburnum, dogwood, and hydrangea
  • Annuals and perennials: shasta daisy, hibiscus, dahlia, and lavender

These bugs typically affect a wide range of plants, including vegetables, herbs, and ornamentals. They can cause damage to leaves, plant stems, and overall growth, appearing as foliar spots or even wilting when left unchecked.

Signs of Damage

The Fourlined Plant Bug’s feeding damage is characterized by various symptoms:

  • Translucent spots: 1/16 to 1/8 inch in diameter caused by the bug’s toxin
  • Wilting: Damaged areas may become necrotic, leading to leaf wilting

Examples of damage may include discolored foliage (greenish-yellow with black dots) on mint and basil or spotted leaves and stems on ornamentals like geranium and zinnia.

Affected Plant Signs of Damage
Mint Discolored foliage, translucent spots
Basil Wilting, translucent spots
Geranium Spotted leaves and stems
Zinnia Spotted leaves and stems

As the Fourlined Plant Bug is a pest that can cause significant damage to plants, it’s essential to remain vigilant in identifying and managing their presence in your garden. With proper care and attention, you can keep your plants healthy and thriving.

Feeding Mechanism and Impact on Plants

Four-lined plant bugs have piercing-sucking mouthparts. They use these mouthparts to feed on plant tissues by injecting their saliva into the plant and then sucking out the liquefied plant materials.

Due to this feeding behavior, plants lose chlorophyll, causing a distortion in their appearance. Moreover, it leads to the formation of dead plant tissue. The overall impact of Four-lined plant bugs on plants can be summarized as below:

Pros:

  • None

Cons:

  • Loss of chlorophyll
  • Distortion of plant appearance
  • Formation of dead plant tissue
Impact on Plants Example
Loss of chlorophyll Plants get a pale appearance and may lose their capacity for photosynthesis
Distortion Leaves may become twisted, curled, or otherwise malformed
Dead plant tissue Necrosis spots or areas of dead tissue may appear on leaves and stems

In conclusion, the feeding mechanism of Four-lined plant bugs has a negative impact on plants, causing the loss of chlorophyll, distortion in plant appearance, and creating dead plant tissue. Educating yourself on the Four-lined plant bug can help you recognize and address any potential infestations in your garden.

Control and Management

Monitoring

Monitoring fourlined plant bugs is essential for timely intervention. Check your plants frequently in late spring, when these pests are most active. Their nymphs are red or reddish-orange with dark wing pads and black dots, while adults have yellowish-green bodies and black antennae, with four longitudinal black lines on their wings covers 1.

Chemical Controls

Effective chemical control measures for fourlined plant bugs include insecticidal soap and horticultural oil. Consider these options:

Insecticidal Soap

  • Pros: Safe for most plants, effective on soft-bodied insects
  • Cons: Alleged irritation to human skin, direct contact with insects required

Horticultural Oil

  • Pros: Environmentally friendly, safe for beneficial insects
  • Cons: Potential for plant damage in high temperatures, may require multiple applications

Neem Oil

  • Pros: Organic solution, disrupts insect’s life cycle
  • Cons: Less effective on adult insects, may cause mild stress to plants

Cultural and Mechanical Controls

Implement these cultural and mechanical control methods to manage fourlined plant bugs:

  • Prune affected plants to remove damaged areas
  • Use a strong spray of water to dislodge bugs from plants
  • Regularly clean up garden debris to eliminate hiding places

Biological Controls

Biological control of fourlined plant bugs relies on their natural predators, such as spiders and predatory insects like minute pirate bugs. Enhance your garden’s ability to attract these beneficial insects by:

  • Planting a variety of flowering plants
  • Avoiding excessive use of chemical pesticides
  • Providing a suitable habitat for predators, like a pile of leaves or a small wood pile

Footnotes

  1. UMN Extension – Fourlined Plant Bugs 2 3

  2. University of Florida Entomology Department 2

  3. University of Maryland Extension – Plant Bugs on Flowers 2 3

  4. Wisconsin Horticulture – Four-Lined Plant Bug

  5. NC State Extension Publications – Fourlined Plant Bug

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Four Lined Plant Bugs

 

Subject: Four Lined Plant Beetles, yellow & green
Location: Naperville, IL
July 1, 2013 6:21 pm
Hi Daniel~
Happy July! It’s been a long time (I think) since you’ve had one of these four-lined plant beetles (Poecilocapus lineatus) depicted, and I’ve never seen them around my neck of the woods until this year. They’re munching on some hydrangea leaves, and I found this yellow one and this green one on the same leaf. They’re very pretty little pests. All the best to you!
Signature: Dori Eldridge

Four Lined Plant Bug
Four Lined Plant Bug

Hi Dori,
Thanks for the new submission, however we have a correction to make to your text.  You have the scientific name correct, but your common name is not.  This is a True Bug, not a Beetle.  True Bugs have piercing/sucking mouthparts and they do not chew.  The brown spotting on the leaves might be due to the feeding which involves sucking nutritious fluids from the plants.  According to BugGuide:  “nymphs and adults feed preferentially on members of the mint family (wild mint, catnip, peppermint, spearmint, hyssop, oregano) but will attack a variety of wild plants (thistle, dandelion, burdock, tansy, loosestrife, sumac) as well as cultivated flowers (carnation, geranium, chrysanthemum, snapdragon, phlox) and crops (alfalfa, ginger, currant, raspberry, cucumber, lettuce, pea, potato, radish, squash).”  Hydrangeas are not mentioned as a food plant, but lists of food plants can often be incomplete.  Thanks again for supplying us with excellent new images of some Four Lined Plant Bugs,
Poecilocapsus lineatus.

Four Lined Plant Bug
Four Lined Plant Bug

Hi again~
It occurred to me after I sent these photos that these are not beetles at all, but rather, four-lined plant bugs, as in true bugs and hemipterans, not coleopterans. Sorry for the confusion; earlier today, I was watching a ladybird beetle larva molt into an adult, so I had beetles on the mind.
All the best,
Dori

 

Letter 2 – Four Lined Plant Bug

 

Subject: not sure of this bug
Location: Missouri, US
May 14, 2015 12:27 am
while pulling weeds I found this little fella
I honestly don’t even know where to begin with an identification
I cropped the first pic and the second I left the same for size comparison
Signature: Stolz

Four Lined Plant Bug
Four Lined Plant Bug

Dear Stolz,
This is a Four Lined Plant Bug,
Poecilocapsus lineatus, and according to BugGuide:  “nymphs and adults feed preferentially on members of the mint family (wild mint, catnip, peppermint, spearmint, hyssop, oregano) but will attack a variety of wild plants (thistle, dandelion, burdock, tansy, loosestrife, sumac) as well as cultivated flowers (carnation, geranium, chrysanthemum, snapdragon, phlox) and crops (alfalfa, ginger, currant, raspberry, cucumber, lettuce, pea, potato, radish, squash).”

Letter 3 – Four Lined Plant Bug: Adult and Nymph

 

Subject: Red bugs!
Location: Michigan
June 6, 2016 5:51 pm
Hi Bugman. Found these in my garden. June 6.. They are devouring my butterfly bush and asters. What are they?
Signature: MiGardener

Four Lined Plant Bugs
Four Lined Plant Bugs

Dear MiGardener,
You have both winged adults, and flightless, red nymphs of the Four Lined Plant Bug,
Poecilocapsus lineatus.  According to BugGuide:  “nymphs and adults feed preferentially on members of the mint family (wild mint, catnip, peppermint, spearmint, hyssop, oregano) but will attack a variety of wild plants (thistle, dandelion, burdock, tansy, loosestrife, sumac) as well as cultivated flowers (carnation, geranium, chrysanthemum, snapdragon, phlox) and crops (alfalfa, ginger, currant, raspberry, cucumber, lettuce, pea, potato, radish, squash).” 

Four Lined Plant Bugs
Four Lined Plant Bugs

Letter 4 – Immature True Bug may be Four Lined Plant Bugs

 

Subject: Red Beetle with black band at top of the body
Location: Minneapolis, MN
June 1, 2014 1:21 pm
Help! Can you IDENTIFY? My normally healthy rudbeckias are all shriveling up and I looked today and saw these on them and other plants which are also shriveling up – echinacea, lead plant, other daisy type plants etc. eating the leaves.. It’s springtime (June 1)
Signature: Thank You!

True Bug Nymphs
True Bug Nymphs

This is not a beetle.  It is a True Bug in the suborder Heteroptera, but we have not had any luck determining a species for you.  Nymphs can be very difficult to identify to the species level.

True Bug Nymph
True Bug Nymph

 

Authors

  • 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
Tags: Four Lined Plant Bug

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6 Comments. Leave new

  • These will destroy flower and veg gardens. In my veg garden, they are on the beans, but they prefer a weed that also grows there, so I let the weed grow. They do not eat any of the mints in my garden. Best way to control them is to burn the cuttings from woody perennials (for example, mums need to be cut back three times before July Fourth. Burn those cuttings so the four-lined bugs cannot hatch out in compost). They lay eggs in tips of new growth, so follow through with cutting back to the ground and burning stems after blooming when possible. This will not eliminate them but can keep them in control. Neem oil, insecticidal soap or a good squashing are suitable when seen on plants, but they are hard to catch. They hatch in waves, info says there are two hatchings each year, but I believe it is more in warmer Zones.

    Reply
  • I don’t believe in BuG Carnage, but if it’s eating my veggies, it has to go. I do sacrifice some tomato leaves to the tomato hornworms every year and plant moonflowers and petunias for the moths.

    Reply
    • We also draw the line with hemipterans that live in large quantities on our plants, like aphids and keeled-back treehoppers.

      Reply
  • I think these are nymphs of the four-lined plant bug, Poecilocapsus lineatus. See http://bugguide.net/node/view/13224/bgimage

    Reply

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