Winter Moth

The winter moth (Operophtera brumata) is an inconspicuous but harmful pest that is mainly active in late autumn and winter. In spring, its caterpillars cause severe feeding damage to fruit trees, berry bushes and ornamental shrubs.

Life cycle

The winter moth belongs to the group of night-flying moths. Its life cycle is perfectly adapted to the cold season:

• Flight period: The inconspicuous moths emerge from October to December. Only the males can fly – the wingless females crawl up the tree trunks.
• Egg-laying: The females lay their eggs in bark crevices, buds or branch forks.
• Overwintering: The eggs overwinter well protected on the branches.
• Caterpillar stage: In spring, usually in April, the green caterpillars hatch just as the buds are breaking. They feed on leaves, buds and blossoms.
• Pupation: After about four to six weeks, the caterpillars drop to the ground and pupate there until the following autumn.

Damage in the garden

Winter moth caterpillars are typical spring pests. They feed on young leaves, blossoms and buds, leaving plants looking bare. Particularly affected are:

• Apple and plum trees
• Blackcurrants, redcurrants and gooseberries
• Oaks, maples and other deciduous trees

A heavy infestation weakens the plants, reduces the yield and can impair bud formation the following year.

Prevention and control

Winter moths can be effectively kept in check with simple, organic measures:

• Fit grease bands in autumn (October/November) to stop the wingless females from crawling up the trunk.
• Put up nest boxes: tits and other birds eat many of the caterpillars.
• Loosen and mulch the soil to disrupt pupation.
• Pheromone traps can help detect the extent of an infestation.

Chemical products are usually unnecessary in the home garden – organic gardeners rely on preventive care and encouraging beneficial insects.

Conclusion

The winter moth is a classic "winter pest" with a major impact on spring growth. Anyone who fits grease bands in autumn and encourages beneficial insects can keep this pest well under control – without any chemicals.