Nysius

Nysius is a genus of true bugs in the family Lygaeidae, commonly referred to as seed bugs. Members of this genus are small to medium-sized, with elongated bodies and varied coloration that typically helps camouflage them on dry plant material. The genus is widespread, with many species found in temperate and warmer regions around the world, including North America, Europe, and parts of Asia and Africa.

Biology and ecology

Nysius species exhibit incomplete metamorphosis, progressing from eggs to several nymphal instars before becoming adults. Both nymphs and adults feed on seeds, using piercing-sucking mouthparts to extract contents from developing fruits and seeds. Diets are broad and include seeds from grasses and broadleaf plants; some species are opportunistic and may shift to crops when seeds are plentiful. Adults often overwinter in sheltered habitats such as leaf litter or crop residue and can migrate into fields during seed set in spring.

Distribution and habitat

The genus is cosmopolitan, with species adapted to a range of habitats including agricultural fields, grasslands, and disturbed areas. Population dynamics are closely tied to seed production in host plants, and outbreaks can occur when seed crops are abundant.

Economic importance

Several Nysius species are agricultural pests due to direct seed damage, reduced germination, and yield losses in crops such as cereals, sunflowers, and legumes. Management generally relies on monitoring and threshold-based insecticide applications, along with cultural practices that reduce seed availability and overwintering sites.

Taxonomy

Nysius comprises multiple described species. Taxonomic placement has varied with revisions in seed bug classifications, and some authorities classify related species within closely related genera in Lygaeidae.