Columbine duskywing

The Columbine duskywing (Erynnis lucilius) is a butterfly species within the Hesperiidae family, commonly known as skippers. While many skippers are viewed as harmless, this specific species is recognized by gardeners as a pest due to its larval stage's specialized feeding behavior on plants of the genus Aquilegia.

Systematically, this insect belongs to the order Lepidoptera. Its life cycle involves complete metamorphosis, consisting of the egg, larval (caterpillar), pupal, and adult stages. The adult butterfly is cryptic in color, often blending into the soil or leaf litter, which makes the monitoring of the adult population quite challenging during the flight season.

The host plants for the larvae are exclusively within the Aquilegia genus. Upon hatching, the young caterpillars begin feeding on the leaves. They are notorious for their habit of creating protective shelters by folding or rolling the leaves and stitching them together with silk. This behavior makes them extremely difficult to reach with standard surface-applied pesticides.

The damage caused by the Columbine duskywing is primarily aesthetic, though severe infestations can significantly impact the health of the plant. By consuming leaf tissue and potentially attacking the buds, the larvae reduce the plant's ability to photosynthesize and bloom effectively. Heavy feeding can lead to stunted growth and premature yellowing of foliage.

Effective management strategies for Erynnis lucilius center on integrated pest management (IPM) practices. Gardeners should manually remove and destroy any rolled or folded leaves found on columbine plants throughout the season. For larger infestations, biological controls such as Btk (Bacillus thuringiensis kurstaki) are highly effective when applied while the caterpillars are young and actively feeding.