Puss moth

The Puss moth (Harpyia) is a genus of moths belonging to the Notodontidae family. The most common species are found feeding on willow and poplar trees.

Adult moths are quite large, with a wingspan reaching 70-80 mm. Their wings are typically white with distinctive dark, wavy, zig-zagging patterns across the surface.

The caterpillars are highly recognizable due to their unique shape. They possess two long, whip-like tails at the rear end which they can vibrate when threatened.

The larvae exhibit vibrant colors ranging from bright green to brown, often featuring a purplish saddle-shaped marking on their backs, making them visible on foliage.

The pupae are dark and robust, encased in hard, woody cocoons that the larvae construct by chewing into the bark or attaching them securely to trunks.

The primary hosts for the Puss moth are trees in the Salicaceae family, specifically various species of willow and poplar trees in nurseries and landscapes.

The pest is particularly damaging to young trees, where it can consume large portions of the canopy, hindering the plant's natural growth and development.

In managed landscapes or ornamental tree rows, the moth can cause severe defoliation, which negatively impacts the aesthetic value of the plantings.

The caterpillars are voracious feeders that strip leaves down to the midribs, a process that weakens the tree's immune system and overall vigor.

Chronic infestations over several growing seasons lead to stunted wood growth, premature leaf drop, and higher susceptibility to secondary fungal infections.

Adult moths typically emerge in late spring or early summer, with timing dictated by regional temperature shifts and soil warming patterns.

Females deposit eggs singly or in small clutches on the upper surfaces of leaves, coinciding with the peak period of vegetative growth for host trees.

Caterpillars are active from mid-June through August, a period during which they consume significant amounts of biomass to fuel their development.

As autumn approaches, the fully grown caterpillars abandon the canopy to seek out sheltered sites on the trunk or branches to begin pupation.

The insects overwinter as pupae within their protective cocoons, remaining dormant until the return of favorable temperatures the following year.

The most prominent sign of infestation is skeletonized foliage, where leaves have been consumed leaving only the skeleton of veins behind.

Close inspection of the tree canopy during the summer will often reveal the presence of caterpillars, which are easily identified by their odd morphology.

Hard, bark-like cocoons found in the crevices of trunks or on branches are a clear indicator that the pest has successfully completed a life cycle.

Accumulation of frass (caterpillar droppings) on the ground underneath the canopy indicates a significant feeding presence above.

Severe infestations often result in canopy thinning and premature leaf drop, leaving the branches visibly bare well before the natural autumn season.

Mechanical removal is a practical approach for small trees; picking off larvae by hand can significantly reduce damage if caught early.

Cleaning tree bark and removing loose scales during winter dormancy can help destroy overwintering pupae and lower the pest pressure for the next season.

Biological insecticides, particularly those containing Bacillus thuringiensis, provide a safe and effective way to manage young larvae without harming the environment.

In cases of heavy infestation on larger specimens, targeted chemical treatment with selective insecticides may be necessary to preserve tree health.

• Perform frequent monitoring of tree canopies throughout June and July.
• Encourage the presence of birds and predatory insects that feed on larvae.
• Maintain tree vitality through appropriate irrigation and soil management.