Yellow-tail moth

The Yellow-tail moth (scientific name Porthesia, commonly identified as Euproctis similis) is a lepidopteran pest belonging to the family Erebidae. The adult moth is easily recognized by its pure white wings and a distinctive tuft of golden-yellow hair at the tip of the abdomen, from which it derives its common name.

This pest is a polyphagous insect that attacks a wide variety of deciduous trees and shrubs. Common host plants include fruit-bearing trees such as apple, pear, plum, and cherry, as well as forest trees like oak, elm, and hawthorn. In severe infestations, the caterpillars can cause complete defoliation of the canopy, severely weakening the tree's health.

The life cycle involves one generation per year. The larvae overwinter as second or third-instar caterpillars in communal silk nests constructed from leaves tied together with silk threads. As soon as buds begin to burst in early spring, the larvae emerge to feed on developing foliage. By June, the larvae are fully grown and pupate in individual cocoons tucked away on branches.

The damage caused by these insects is characterized by the skeletalization of young leaves, progressing to the consumption of entire leaves as the caterpillars mature. Beyond agricultural impact, the larvae are physically dangerous to humans. They are covered in urticating hairs that can cause severe skin irritation, rashes, and respiratory issues if inhaled or touched.

Effective management strategies rely on integrated pest control. The most reliable mechanical method is the manual removal and destruction of the silk-webbed nests during the winter months while the trees are dormant. During the growing season, if populations remain high, the use of biological insecticides, such as Bacillus thuringiensis, or targeted chemical treatments is recommended.