Boxwood moth (Latin: Cydalima perspectalis) – a dangerous boxwood tree pest.
How to recognize the boxwood moth?
The boxwood moth is a species from the grass moth family (Crambidae). The wingspan of an adult moth is ca. 40 mm. Both pairs of wings are white with a brown border.
There are also moths with mainly light brown wings with purple sheen and white moon-shaped spot.
Larvae – hairy caterpillars, feeding on plants, growing up to the length of 35 – 44 mm.
The caterpillars are initially greenish in colour with brown longitudinal lines, later they become darker, brownish. Their head is black.
Females lay round yellow eggs 1 mm in diameter on the underside of leaves, deep inside a healthy plant. Greedy larvae 1- 2 mm in size hatch from the eggs and within ca. 4 weeks they reach 35 – 40 mm in length. In Poland 2 – 3 generations develop during a year. The second generation caterpillars overwinter in an hibernaculum made of two boxwood leaves joined with self-spun silk. Adult moths usually fly at night from April to September.
How to recognize that boxwood moth has been foraging on your shrubs?
When you look at boxwood shrubs you can notice:
- nibbled leaf edges,
- whole leaves eaten
- frass (excrement) left on leaves
- defoliated shrubs
- webbing spun on the shrubs
- shrubs sick and dying, in consequence of the plant damage.
Attention! The caterpillars look for new host plants.
The insect has been observed on spindles (e.g. winged spindle – Euonymus alatus and Japanese spindle – E. japonicus), hollies (Ilex purpurea), cotoneasters (Cotoneaster spp.), English laurels (Prunus laurocerasus) and other shrubs.
The boxwood moth has no natural predators in Poland and we have to fight it ourselves.
How to fight the caterpillars?
An insecticide containing the Bacillus thuringiensis bacteria has to be used as soon as the caterpillars appear. The insecticide is registered for professional users.
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