Purple emperor

The Purple emperor (Apatura iris) belongs to the order Lepidoptera and the family Nymphalidae. While widely recognized for its aesthetic value, its larval stage is a phytophagous pest that can feed on the foliage of various willow and poplar species in commercial or ornamental settings.

This species primarily feeds on host plants such as goat willow (Salix caprea) and gray willow (Salix cinerea). In cases of high population density, the larvae can cause significant defoliation, which affects the health and growth rates of young or sensitive trees.

The biology of this pest involves a single generation per year. Larvae overwinter in the 2nd or 3rd instar, finding refuge near buds or within branch forks. During spring, they resume feeding as the sap begins to flow, growing rapidly until they pupate on the underside of leaves by early summer.

Damage occurs primarily through leaf consumption. Larvae often strip the foliage almost entirely, leaving only the midribs and major veins. This extensive feeding reduces the photosynthetic surface area, leading to general weakening and increased susceptibility to secondary stressors.

Management and control strategies include monitoring for larval activity in early spring. If threshold levels are exceeded, the use of contact or systemic insecticides is recommended. Biological control, specifically using products containing Bacillus thuringiensis, provides an effective and environmentally conscious solution.