Two-striped grasshopper

Systematic position: The two-striped grasshopper (Melanoplus bivittatus) belongs to the order Orthoptera and the family Acrididae. It is recognized as one of the most destructive grasshopper species in North America, frequently causing economic losses in agricultural regions due to its aggressive feeding habits.

Biology and life cycle: This species undergoes hemimetabolous development. It overwinters in the egg stage, with eggs deposited in the soil in late summer. Nymphs emerge in the spring and progress through five developmental stages (instars). The duration of the life cycle is heavily dependent on temperature, with warmer conditions significantly accelerating the maturation of nymphs into adults.

Crops and economic impact: As a polyphagous insect, it feeds on a diverse range of host plants. Major affected crops include cereals such as wheat and barley, corn, alfalfa, soybeans, and various horticultural crops. High-density infestations can lead to total destruction of fields, especially during drought years when natural forage is scarce and insects migrate to irrigated fields.

Nature of damage: Both nymphs and adults consume leaf tissue, often starting from the margins and proceeding to strip the entire plant. Beyond the direct loss of biomass, the injury disrupts plant physiology and reduces the yield potential. In severe cases, the stems are consumed, which compromises the structural integrity of the crop and increases harvest losses.

• Tillage practices, specifically late summer or fall plowing, to destroy egg pods.
• Removal of weeds from field margins and fence lines to eliminate breeding sites.
• Application of insecticides at the nymphal stage to prevent maturation and large-scale crop loss.
• Monitoring population density using sweep net sampling to trigger timely interventions.
• Biological control through the encouragement of natural predators like birds and parasitic wasps.