December moth

The December moth (Poecilocampa populi) is a member of the Lasiocampidae family, commonly found across Europe and parts of Asia. Unlike many moth species, this insect is active during the late autumn months, with adult moths typically appearing from September through December, which makes its reproductive cycle distinct from summer-active pests.

This species is highly polyphagous, meaning it feeds on a wide variety of deciduous trees. Its host plants include poplar, willow, birch, lime, oak, and various fruit trees such as apple, pear, and plum. Because of its diet, it can be a significant nuisance in managed parks, street plantings, and commercial orchards.

The life cycle begins with eggs laid in clusters on the branches or trunks of host trees, where they undergo diapause throughout the winter. As spring arrives and buds begin to burst, the larvae hatch and start feeding aggressively. The caterpillar stage lasts for several weeks, during which they grow significantly before spinning tough, camouflaged cocoons to pupate.

The primary damage is caused by the caterpillars, which consume leaf tissue extensively. In cases of high infestation, they can cause widespread defoliation of the canopy. Such damage weakens the trees, inhibiting photosynthesis and reducing the overall vitality of the plant, which makes them more susceptible to subsequent stressors like drought or secondary infections.

Control strategies for the December moth involve a mix of physical and chemical methods. Winter pruning and the removal of visible egg masses can significantly reduce the population. During the spring larval stage, if infestation is severe, applying approved systemic or contact insecticides or biological agents like Bacillus thuringiensis can effectively curb the damage to the trees.