What is the role of Lygus bugs as pests?

Lygus bugs, particularly the Lygus lineolaris species, are recognized as significant pests in agricultural settings, especially in alfalfa grown for seed. They play a detrimental role by feeding on plant sap, which can severely affect the plant's health and productivity. Their feeding damages the plant tissues, leading to stunted growth and reduced seed production. In alfalfa, this is particularly concerning since the quality and quantity of seed harvested can be drastically diminished if Lygus populations are not managed effectively. The economic implications of their damage establish them as a top concern for growers in regions where alfalfa is cultivated.

In contrast, other choices describe either minor roles or incorrect functions of Lygus bugs. They are not classified as beneficial insects; rather, they have no positive impact on crop health. Additionally, while they may inflict damage on various parts of plants, including stems and leaves, they do not restrict themselves to just infesting roots, and their impact extends beyond just a minor pest status on grass.