Tarnished Plant Bug

The tarnished plant bug (Lygus lineolaris) is a widespread agricultural pest that affects many different types of plants. It is a species of plant-feeding insect in the family Miridae.

Host Plants

The tarnished plant bug has a broad host range and has been reported to feed on over half of all cultivated plants. Its favorite hosts include fruits (apple, pear, peach, raspberry, strawberry), vegetables (snap beans, celery, eggplant, lettuce, pea, potato, sweet corn, tomato), and ornamentals (dahlia, aster, calendula, chrysanthemum, cosmos, gladiolus, poppy, salvia, daisy, sunflower, verbena, zinnia, and others).

Regions impacted

Tarnished plant bugs are native to North America and are found throughout the continent, from northern Canada to southern Mexico. They are a major pest in the northeastern United States and eastern Canada, especially in areas with a high concentration of fruit and vegetable production. They are also found in Europe and Asia.

Description

Tarnished plant bugs are small, about 1/4 inch long, with a broad, triangular shape. Their color can vary from mottled yellow to brown, which gives them their “tarnished” appearance. They have a characteristic “Y”-shaped mark on their backs and wingtips that extend beyond their body, covering their abdomen.

Life Cycle

The life cycle of the tarnished plant bug goes through the typical stages of an insect: egg, nymph, and adult. There are typically 2-3 generations per year, though the number can be higher in warmer climates.

Overwintering Stage: Adult tarnished plant bugs overwinter in plant debris, garden waste, or under the bark of trees. As temperatures warm in the spring, the bugs emerge from their overwintering sites.

Egg Stage: Once the temperatures have warmed sufficiently, usually in spring, the females begin to lay their eggs. They insert their eggs into plant tissues such as stems, leaves, or flower buds. A single female can lay up to several hundred eggs during her lifespan, and these eggs will hatch in about a week or two, depending on the temperature.

Nymph Stage: After hatching, the tarnished plant bug nymphs begin feeding on plant tissues. Nymphs resemble the adults but are smaller and do not have wings. As they grow, they go through five instar stages, shedding their skin and increasing in size with each molt. This nymph stage lasts about two to three weeks.

Adult Stage: After the final molt, the nymphs transform into winged adults. These adults will then mate and lay eggs to start the next generation.

The speed at which the tarnished plant bug goes through its life cycle depends on temperature and food availability. In warmer climates, the bugs can go through their entire life cycle in as little as 3-4 weeks, allowing for multiple generations in a single growing season. In cooler climates, the life cycle may take longer, and there may be fewer generations per year.

Damage and Detection

Damage

Tarnished plant bugs are known to cause significant damage to a variety of crops due to their wide host range. They feed on many different parts of plants including leaves, stems, flowers, and fruits, piercing plant tissues with their beak-like mouthparts and sucking out sap.

The damage from their feeding can result in a variety of symptoms, including:

• Deformed or catfaced fruit, especially in strawberries and tomatoes.
• Blackened tips on plants like lettuce and endive.
• Necrotic spots or areas of dead tissue on leaves and stems.
• Wilted and stunted plants or plant parts.
• Bud blasting in flowers, where buds drop before they can open.
• Seed and pod damage in legume crops, which can reduce yield.

Moreover, tarnished plant bugs can also act as vectors for plant diseases, transmitting them from one plant to another as they feed.

Detection

Detecting tarnished plant bugs can be challenging due to their small size and their behavior. They tend to drop from plants when disturbed, and their coloration can provide camouflage among the plant tissues. However, the presence of these bugs can often be inferred by the damage they cause.

Here are some methods to detect tarnished plant bugs:

• Visual inspection: Examine your plants closely for signs of damage and for the bugs themselves. Check underneath leaves and around buds and flowers, where they like to feed.
• Tap or Beat Sampling: Gently tap or beat the plant over a sheet of white paper or cloth. This can cause the bugs to fall off the plant and onto the sheet, where they can be easily seen.
• Sweep Net Sampling: In larger crop fields, a sweep net can be used to sample for tarnished plant bugs. This involves sweeping the net through the vegetation and then examining the contents of the net for the presence of the bugs.
• Sticky Traps: White sticky traps can be placed near the crop. The bugs are attracted to the color and will get stuck on the trap when they land on it.

Regular monitoring of your crops and quick identification of any damage can help catch an infestation early before it becomes a larger problem. Regular inspections are a crucial part of integrated pest management.

Prevention and Control

The control and prevention of tarnished plant bugs involve a multifaceted approach that includes cultural, biological, and chemical methods. Here are some strategies:

Cultural Control

• Sanitation: Remove plant debris and weeds, especially from the border area of gardens or fields, which can serve as host plants or overwintering sites.
• Trap Crops: Plant trap crops (crops that the bugs prefer) around the border of your main crops. Once the bugs are on the trap crops, you can use an insecticide to control them. Examples of trap crops include alfalfa, safflower, sugarbeet, tomato, or beans.
• Row Covers: Use row covers to protect vulnerable crops, especially during periods when adults are laying eggs or nymphs are emerging.

Biological Control

• Beneficial Insects: Several insects are known predators of tarnished plant bugs. These include big-eyed bugs, damsel bugs, minute pirate bugs, and certain species of spiders and lacewings.
• Parasitic Wasps: Some species of parasitic wasps attack tarnished plant bug eggs and nymphs. These wasps are usually more effective when combined with other control methods.

Chemical Control

• Insecticides: If the population of tarnished plant bugs is high and causing significant damage, insecticides may be necessary. Use a product that is effective against tarnished plant bugs and try to choose one that has minimal impact on beneficial insects.

Monitoring

Regular monitoring is key to managing tarnished plant bug populations. This can be done through visual inspections, the use of sweep nets, and sticky traps. Regular monitoring can help detect the bugs early before they can cause significant damage, and it can also help in deciding when and if insecticides are needed.

Always consider the impact of any control method on non-target organisms and the environment. In many cases, an integrated pest management (IPM) approach that combines multiple strategies will be the most effective way to manage tarnished plant bug populations. It’s also important to follow all label instructions when using any pesticide product.