Four-Lined Plant Bug Control: How to Identify, Prevent and Get Rid of Four-Lined Plant Bugs

Poecilocapsus lineatus, or four-lined plant bug, is a garden pest that can be destructive to hundreds of plants in the garden, especially in North America and Canada. It sucks juices out of the plant, especially from the leaves and the terms, making its host unhealthy. To manage the infestation, it is important to be aware of how to get rid of four-lined plant bugs.

The eggs of four-lined plant bugs have an average length of 1.65 millimeters. It has a cylindrical and slight curved body with a light-yellow color upon being laid by an adult. As the eggs get closer to hatching, it turns red. After hatching, they undergo five instars as a nymph in which the color ranges from bright red to bright orange. When it turns into an adult, on the other hand, the easiest way to identify them is through the presence of four black lines in their yellow or green body. The head is orange while the eyes are reddish brown. It has a length of up to 7.5 millimeters and width of approximately 3.5 millimeters.

Four-Lined Plant Bug

Four-Lined Plant Bug Has Four Black Lines in Their Yellow or Green Body

Four-Lined Plant Bug’s Habitat

Four-lined plant bugs overwinter as eggs and they hatch in late spring. At this point, the nymphs will start feeding on your plants, concentrating on the upper side of a leaf. They will continue to feed for up to three weeks until they molt into an adult. When adults mate and females lay their eggs, the latter will be apparent on the upper stem of the host. They can be found in gardens, fields, and can even penetrate inside homes. They most commonly cause infestation from May to July, although this will depend on the climate of your specific location.

Identifying Four-Lined Plant Bug’s Damage

Plants Affected

The four-lined plant bug feeds on more than 250 species of plants. Some of its most common hosts include hyssop, marjoram, spearmint, peppermint, sage, dahlia, chrysanthemum, azalea, sunflower, peony, daisy, snapdragon, and zinnia.


The following are some of the most common signs that will be indicative of the presence of four-lined plant bugs:

  • The leaves will show the most signs. There will be holes on the surface. One thing that will make it easy to determine if they are because of four-lined plant bug is to look at the size of the holes. They must be similar in terms of their size and shape.
  • Four-lined plant bugs will kill the tissue on the surface of the leaves of the host plant. The damage is not only aesthetic, but it will also cause the leaves to turn yellow or brown. This is a result of the deprivation of the nutrients that are essential for its growth.
  • These bugs can also feed on new shoots or young plants. With this, one of the most common symptoms of their presence is the wilting of the host plant.

Results of Infestation

In most instances, the damage from four-lined plant bug can be easily mistaken as a result of leaf spot disease. The damage is mostly aesthetic on the leaves of the plant. This makes it a big problem for ornamental plants as this will make them unattractive. It is seldom that they can lead to huge economic losses, especially because crops are not main hosts. Nonetheless, it can inhibit the flow of nutrients to the other parts of the plant, which can have a critical effect on its health.

Four-Lined Plant Bugs Damage

The Damage is Mostly Aesthetic on the Leaves of the Plant

How to Get Rid of Four-Lined Plant Bugs

Natural and Organic Solutions

Below are some of the solutions that can be effective in the control and elimination of four-lined plant bugs:

  • Hand removal is one of the simplest ways to eliminate these pests, although this will require quite an effort on your end. With this, manual picking is best only if you have to treat a small population. You can also spray water on the plants, which will cause the bugs to fall off the ground. Be sure to pick and kill the bugs. Otherwise, they will just keep returning to the host plant and will wreak havoc.
  • Using floating row cover is also a good solution. This will form a protective barrier on the top of the plant. Nonetheless, when it is time for pollination, you need to take it out. The floating row cover should be made from fine nets, which will still allow sunlight to penetrate and to encourage photosynthetic activity. A garden fabric can also be used to cover the plants and to keep the bugs away.
  • Consider cultural control measures as well. It will be good to plant trap crops around the main crop, which will spare the latter from further damage. Another cultural control that is effective is practicing field sanitation, which also happens to be an exceptional preventive measure. By keeping the garden clean, there will be no attractive breeding ground for the pests. Also, tilling the soil is a good practice to expose the overwintering eggs and to kill them even before they hatch.
  • Another popular method to eliminate four-lined plant bugs is through biological controls. Simply put, this is all about encouraging the presence of natural predators in the garden, which will kill the pest before they can cause damage to your plants. One of the best would be a predatory wasp, which will be effective in destroying egg clusters.

Chemical Solutions

Like in the case of controlling other pests, chemical control should be your last resort. While it can be effective in killing four-lined plant bug, the problem is that it can be toxic even for beneficial insects and pests. They can also be harmful for humans. To prevent such problems, it is best to read the instructions from the manufacturer and make sure to follow it. Proper application is a must to yield a high level of effectiveness. If you will use it for edible herbs, you have to be more careful as it can be toxic for humans. Pay attention to the Days to Harvest specification in the label, which will indicate how long you need to wait before harvest after the application of the pesticide.

Some of the most popular for chemical control of four-lined plant bugs include bifenthrin (Brigade), carbaryl (Carbamine), and acetamiprid (Assail).

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