**Lygus Bugs** (genus *Lygus*), also known as the **Tarnished Plant Bug** (*Lygus lineolaris*), are highly polyphagous (feeding on many plants) true bugs that are severe pests of fruit, vegetable, flower, and seed crops globally. They feed by inserting their piercing-sucking mouthparts into soft plant tissue (especially buds, flowers, and developing seeds/fruit) and injecting toxic saliva. This feeding causes the tissue to die, leading to deformation, stunting, or abortion of the flowers and fruits, resulting in significant yield loss.
Taxonomy and Classification
Lygus Bugs belong to the order Hemiptera (true bugs), family Miridae (Plant Bugs). They undergo incomplete metamorphosis. They are highly mobile, moving rapidly between various host plants (weeds to crops) throughout the growing season. This mobility complicates control efforts as they can quickly reinvade a field.
Physical Description
Adult Lygus Bugs are oval, flattened insects, 1/4 inch long.
- **Appearance (Key ID):** Mottled brown, green, and yellowish-tan, giving a tarnished appearance. A distinct feature is the presence of a small, pale or yellowish **triangle** (scutellum) on the top-center of their back. They are quick to hide or fly when disturbed.
- **Nymphs:** Small, bright green, often resembling small aphids but lacking the aphid’s cornicles and possessing a quick, active gait.
- **Damage Sign (Key ID):**
- **Catfacing:** Stunting and deformity of fruit (e.g., strawberries, peaches).
- **Blasted Buds:** Flowers or buds that die and turn black without opening (e.g., cotton).
- **Seed Damage:** Shriveling and loss of viability in seed crops.
Distribution and Habitat
Lygus Bugs are common throughout North America and are widespread globally. Their habitat includes alfalfa fields, fruit orchards, weedy areas, and vegetable plots. They overwinter in leaf litter and emerge early in the spring.
Behavior and Conflict
The conflict is significant economic crop damage and deformation.
- **Toxic Saliva:** The toxic saliva injected during feeding kills the surrounding cells, and as the plant tissue expands, the dead areas don’t, resulting in the characteristic deformation or “catfacing” of fruits.
- **Reservoir Hosts:** Weeds and non-crop plants (like alfalfa) serve as continuous breeding grounds, allowing the bugs to quickly move into high-value crops.
- **High Mobility:** Their ability to fly and move between crops makes their management challenging.
Management and Prevention
Control is integrated pest management (IPM), relying on weed control and targeted chemical application.
- **Weed Control (Key):** Maintain weed-free borders around crops to eliminate secondary breeding/refuge sites.
- Mow cover crops at the right time to avoid forcing large populations into the main crop simultaneously.
- Use a **sweep net** to monitor bug density in the field and apply insecticides only when the population reaches a proven economic threshold.
- Apply fast-acting insecticides during critical growth stages (e.g., flowering/bud development) to protect the most vulnerable plant parts.
Conservation and Research
Lygus Bugs are managed as high-priority agricultural pests. Research focuses on host plant resistance, developing accurate action thresholds, and implementing biological controls (parasitic wasps) that are effective against the highly mobile insect.