Tussock moths

Tussock moths (genus Orgyia) are a group of moths in the Erebidae family, known for their caterpillars which act as serious defoliators. The adult insects show significant sexual dimorphism: while males have functional wings and are strong fliers, many females are wingless or possess vestigial wings, remaining near their cocoon site to lay eggs after mating.

In terms of classification, they belong to the order Lepidoptera, family Erebidae (formerly Lymantriidae). The most prominent species is Orgyia antiqua, the rusty tussock moth, which is a notorious pest capable of causing significant economic losses in fruit orchards and forest environments by defoliating trees.

The host range is broad, including various fruit trees like apples, pears, and plums, as well as many hardwood forest trees such as oak, willow, and birch. The caterpillars consume foliage rapidly, and when populations reach outbreak levels, they can leave entire branches or trees stripped of their leaves, stressing the plant and reducing overall fruit production.

The life cycle involves overwintering as eggs attached to the female's old cocoon. Upon hatching in spring, the caterpillars begin their feeding phase. They are easily recognizable by their colorful tufts of hair and elongated body setae. These hairs are not just for display; they often contain toxins that can cause allergic reactions in humans and serve as a defense against avian and insect predators.

Effective control measures require a combination of cultural and chemical strategies. During the dormant season, inspect trees and remove egg masses to reduce the following year's population. During the active growing season, monitoring for young larvae is crucial; early intervention with biological insecticides, such as Bacillus thuringiensis, is often effective and environmentally sound compared to broad-spectrum chemical pesticides.

• Manual removal of cocoons and egg masses during winter pruning
• Monitoring for young larvae using sticky traps or visual inspection
• Biological control using predators and parasitoids
• Chemical treatment with selective insecticides during peak feeding