Orgyia thyellina

Systematic position: Orgyia thyellina belongs to the order Lepidoptera and the family Erebidae (subfamily Lymantriinae). Commonly known as tussock moths, these insects are characterized by distinctive hair tufts on the larvae, which are a key identification feature for agronomists.

Affected crops: This species is a polyphagous pest, meaning it attacks a wide variety of plants. It is particularly notorious for damaging fruit trees such as apples, pears, and plums. It can also be found on various deciduous forest trees, posing a threat to both orchards and ornamental landscapes.

Biology and lifecycle: The lifecycle of this moth consists of egg, larva, pupa, and adult stages. Because the adult females often have vestigial wings, their movement is limited, often leading to localized but intense infestations. The insect overwinters primarily in the egg stage, attached to cocoons or tree bark, ready to hatch in the spring.

Damage and economic impact: The larvae are aggressive defoliators. They feed on leaves, moving from slight skeletonization to consuming the entire leaf blade. Large infestations can result in total defoliation, which severely stresses the host plant, reduces yield, and weakens the tree's overall vigor, making it susceptible to secondary pathogens.

Protection measures: Integrated Pest Management (IPM) is essential for controlling this moth. Cultural practices, such as pruning and destroying egg clusters during the dormant season, are highly effective. During the growing season, if thresholds are exceeded, chemical control using targeted insecticides or biological agents like Bacillus thuringiensis should be implemented.

• Manual removal of egg masses
• Application of biological insecticides
• Use of pheromone traps for population monitoring
• Supporting natural predator populations