Median wasp

Systematic position: The median wasp (Dolichovespula media) belongs to the order Hymenoptera, family Vespidae. It is a social wasp species known for constructing large, paper-like nests, often suspended in the branches of trees or shrubs, or attached to the structures of buildings.

Affected crops: This insect primarily targets orchard crops and vineyards. It is attracted to ripening fruits, including apples, pears, plums, and grapes. By piercing the skin of the fruit, the wasps feed on the sugary juices, causing significant physiological stress to the plant tissue and inviting secondary fungal infections.

Biology and life cycle: The life cycle begins in spring when the queen, having survived the winter, emerges to build a new nest. Throughout the summer, the colony grows, with workers performing various tasks including nest maintenance and food foraging. The colony declines in late autumn when the queen and workers die, leaving only the newly mated queens to hibernate.

Damage character and economic importance: The economic damage is characterized by direct loss of market-ready fruit. Beyond the physical consumption of fruit flesh, the presence of damaged crops results in rapid decay, making affected fruits unmarketable. Their aggressive nature when the nest is disturbed poses a health risk to workers during harvesting.

• Conduct regular garden patrols to identify and remove nests early in the season.
• Maintain orchard sanitation by promptly removing fallen or decaying fruit from the ground.
• Deploy bait traps containing sugar-based solutions to reduce the adult wasp population.
• Install protective netting over individual high-value fruit clusters such as table grapes.
• Utilize appropriate insecticide treatments to eliminate nests located in high-risk areas.