Paper wasp Polistes macaensis

Polistes macaensis is a social paper wasp species belonging to the Vespidae family within the Hymenoptera order. While they are often viewed as predators of various caterpillars, they can become significant agricultural pests when their population density increases, particularly in fruit-growing regions and greenhouse operations.

The biology of this species is characterized by the formation of paper-like nests made of chewed wood fibers mixed with saliva. The colony is founded by a queen who survives the winter and starts building the structure in early spring. As summer progresses, the number of workers grows, which often aligns with the harvest season, leading to conflicts between the insects and farmers.

The primary damage caused by these wasps is concentrated on ripening fruits, such as grapes, pears, peaches, and plums. The wasps chew through the skin of the fruit to reach the sugary juice inside. This behavior leaves the fruit vulnerable to secondary infections, including fungal rots and fermentation, which significantly reduce the marketability and yield of the harvest.

In addition to direct crop damage, their presence poses a management challenge during the harvesting period. The aggressive defense of the colony makes maintenance and harvesting operations in orchards and vineyards difficult. This is particularly problematic in intensive cultivation systems where human activity is high and the density of wasps is unchecked.

To manage Polistes macaensis populations, agricultural producers should utilize the following integrated pest management strategies:

• Regular inspections of farm structures and tree canopies to identify and remove early-stage nests.
• Deployment of specialized attractant traps to divert wasps away from ripening fruit.
• Application of protective bagging for high-value fruit clusters.
• General sanitation, including the removal of rotting fallen fruit that attracts wasps to the area.