Red-underwing skipper

Systematic position: The red-underwing skipper (Spialia sertorius) belongs to the family Hesperiidae, order Lepidoptera. While many skippers are viewed as pollinators, the larval stage of this specific species is recognized as a potential feeder on plants, occasionally causing localized damage to host vegetation in garden settings.

Affected plants: The primary food sources for the larvae are members of the Rosaceae family. The most frequently attacked plants include species of Sanguisorba (burnet) and Potentilla (cinquefoil). These plants are common in both wild habitats and ornamental garden landscapes, making them susceptible to feeding pressure.

Biology and lifecycle: The species typically undergoes one or two generations per year, depending on regional temperature and climate. Eggs are laid individually on the underside of host leaves. Upon hatching, the larvae construct protective shelters by folding and webbing leaves together with silk. This protective structure allows them to feed and grow safely from predation during the larval stage.

Damage and economic significance: The damage manifests as leaf skeletonizing, irregular notches in leaf edges, or complete consumption of tender leaf tissue. While the red-underwing skipper rarely causes total crop destruction, its feeding activity diminishes the aesthetic value of ornamental plants and stresses young specimens, which can make the vegetation more susceptible to secondary pathogenic infections.

Protection measures: Effective management strategies involve a combination of monitoring and intervention. It is advised to inspect host plants regularly, especially in spring, for silk-webbed leaf nests. Manual removal of these nests is often sufficient for small garden infestations. If larvae populations exceed acceptable thresholds, the application of biological pesticides containing Bacillus thuringiensis or suitable synthetic insecticides is recommended.