Box tree moth (Cydalima perspectalis)

Size:

• Caterpillars: up to 5 cm long
• Butterflies: Wingspan 35 to 45 mm

Look:

• Butterfly: White with a brown border and a narrow brown central stripe, rarely a completely brown form
• Caterpillars: Green with black longitudinal stripes and white warts, black head
• Eggs: Pale yellow, laid in scale-like patterns on the undersides of leaves

Way of life:

• 2 to 3 generations per year in Switzerland
• Overwintering as a young caterpillar in a cocoon inside the boxwood tree
• The moths are active from May to October, fly at night and are attracted to light.
• Mass reproduction without natural predators

Reproduction:

• Eggs are laid in clutches of 20 to 30 on the undersides of leaves.
• Larvae hatch after 3 to 10 days.
• Caterpillar development over several weeks with strong feeding activity
• Pupation in white cocoons between leaves

Infestation sites:

• Boxwood shrubs in gardens, parks, cemeteries
• Boxwood pots, hedges, globe-shaped trees
• Particularly affected: Boxwood hedges with a dense structure

Nutrition:

• Exclusively boxwood species (Buxus)
• Leaves and green bark are eaten.
• In case of severe infestation, defoliation and girdling of the shoots are necessary.
• Adult animals do not ingest food

Behave:

• Caterpillars hide inside the plant.
• Spiders spin white webs around themselves and leave droppings.
• The damage begins subtly, but then quickly leads to complete destruction.

Economic damage:

• Extensive damage to ornamental gardens, public parks and cemeteries
• Significant maintenance and pruning effort
• Costs for replacement plantings or alternative planting

Plant damage:

• Complete defoliation leading to total loss of leaves
• Destruction of the green bark leads to the death of entire shoots.
• Visible webs and droppings spoil the aesthetics.

Spread:

• Distribution via wind, moth flight and plant trade
• No natural regulation by predators in Europe
• Rapid spread throughout Switzerland

Early detection:

• Visual inspection of leaves and inside the plants
• Webs and droppings as clues
• Monitoring with pheromone traps during the flight period of the moths
• Control particularly in spring and late summer

Cultural measures:

• Pruning of infested shoots, collecting of caterpillars
• Disposal of infested clippings in closed bags
• Do not store on the compost heap

Preventive control:

• Use of insecticides to control larvae
• Repeated spraying is necessary across multiple generations.