Tarnished Plant Bug: What Are They and What To Do About Them?

The Tarnished Plant Bug (Lygus lineolaris) is a member of a very large and diverse insect family of bad garden bugs which feed on plant parts including flowers and buds.

They are abundant throughout Canada and the United States.

These bugs have piercing, sucking mouthparts.

tarnished plant lygus bug

They feed by sucking the sap from plants.

In the process, they inject a toxic digestive enzyme.

This helps them break down plant tissues but causes a great deal of damage.

Both adult bugs and nymphs are problematic for many different types of plants.

They feed on every part of the plant, including the blossoms, leaves, stems, and fruit.

Horticulture Tips: Tarnished Plant Bug

What Do Tarnished Bugs Look Like?

They’re called Tarnished Bugs because of the copper brown color.

They have oval bodies, and their wings are a coppery shade of brown with reddish, bronze, or yellow mottling.

The forewings are marked with a yellow triangle and black tips.

Adult bugs are quite small at only a quarter of an inch long.

The nymphs are very similar to the adults, but they are smaller, wingless, and yellowish green.

The eggs of the Tarnished Plant Bug look like tiny bananas.

They are long, yellow, and curved.

You’ll usually find their eggs inserted in the tips of plant growth and young, tender leaves.

How Do Lygus Plant Bugs Damage Plants?

These pests can do a great deal of commercial damage to fruits and vegetables, and they also enjoy attacking your home garden.

If your garden is infested you’ll be able to see them and you’ll notice the symptoms in your plants.

Damage can include:

  • Head vegetables such as cauliflower may take on a bronze tinge because of multiple Tarnished Bugs feeding on the flower buds.
  • Dead or necrotic spots may appear in the leaves, stems, buds, and fruits if attacked by Tarnished Bugs.
  • Young buds or fruit may wither and fall from the plant.
  • Fruit on the vine or limb may become deformed.
  • Vegetative growth may be deformed or reduced.
  • Seeds may be damaged.

Plants will begin wilting and dying.

Fruits will become distorted, and strawberries and tomatoes will become “cat-faced.”

You will see cloudy spots on tomatoes, strawberries, and other fruit.

Lettuce may turn yellow and develop dead or necrotic spots.

Tarnished Plant Bugs like to feed on the flower buds of pepper and eggplant, and this will cause the buds to drop from the plants.

When the bugs attack peach and pear trees, you’ll see spots on the fruit, and the fruit will not develop to full size.

In addition to damaging individual plants with their feeding, when they move from plant-to-plant, they can spread a condition known as fire blight disease which affects shrubs and trees.

What Plants Are At Risk?

Although Tarnished Bugs may begin their seasonal feasting with early sprouting weeds, they quickly move on to cultivated plants.

Some of their favorites include:

  • Asian Greens
  • Strawberries
  • Cucumbers
  • Swiss Chard
  • Cauliflower
  • Tomatoes
  • Asparagus
  • Potatoes
  • Eggplants
  • Peppers
  • Cabbage
  • Broccoli
  • Turnips
  • Peaches
  • Lettuce
  • Carrots
  • Celery
  • Beans
  • Beets
  • Pears

Their predation is not limited to these fruits and vegetables, but if you are growing these crops, you should be on the lookout as these are the preferred sources of sap.

The Lifecycle of the Tarnished Lygus Plant Bug

Both adults and nymphs can overwinter in garden debris, weeds, and shrubs.

In the springtime, they emerge and begin feeding on budding plants and seedlings.

The adults lay eggs in the tender young tissues of plants.

Within a week, these eggs hatch and a whole new generation of nymphs begin feeding.

Within three or four weeks, the nymphs will transition into adult bugs.

These prolific bugs can produce as many as five generations in a single year.

What Can You Do about LygusPlant Bugs?

Set up physical barriers to keep Tarnished Plant Bugs out by installing floating row covers.

Additionally, placing white sticky traps about 2’ feet above the ground throughout your garden will attract them.

You should check the traps frequently to be sure you are not also killing off beneficial bugs.

Plants with a serious infestation may need to be sprayed with pyrethrin or dusted with a substance known as sabadilla.

For the most effective, chemical-free control, you’ll need to follow a series of carefully orchestrated pest management steps.

#1 Remove any debris and weeds around your garden.

Tarnished Plant Bugs are especially fond of:

  • Lamb’s Quarters
  • Wild Mustard
  • Smartweed
  • Chickweed
  • Dandelion
  • Pig Weed
  • Curly Dock

#2 In advance of planting your crops, you’ll want to plant some pollen-producing plants to attract pirate bugs, damsel bugs, and big-eyed bugs.

These are natural plant bug predators which make short work of Tarnished Plant Bugs and their kin.

#3 Place some white sticky traps low to the ground around your garden to catch Tarnished Plant Bugs as they emerge from overwintering.

Again, take great care to be sure you are not killing off your garden friendly insects.

If you see it, stop using the white sticky traps.

#4 When you plant your spring garden, set up row covers made of spun poly as soon as you set your plants out.

This will block access to Tarnished Plant Bugs.

Place the row covers right on the plants, or set up supports to create tunnels.

The most important thing is to make sure the edges of the row covers are sealed securely against the soil.

#5 As your new plants begin to grow, you may wish to spray them with Kaolin clay, which will confuse plant bugs and prevent them from landing on the plants, feeding on them and laying eggs.

#6 As your plants grow and develop, spray them periodically with a garlic spray to repel the bugs and prevent them from landing, feeding and egg laying.

#7 Continue to protect your plants using floating row covers.

#8 At the end of the season, after you have harvested your crops, be sure to clear away all debris and remove all dead plants from your garden.

Good housekeeping practices will deprive Tarnished Plant Bugs of a place to overwinter.

While this will not eliminate their possibilities of hiding places (they will overwinter in tree bark), it will go far toward reducing their numbers.