Pests & Diseases

Box Tree Moth

Box Tree Moth: A Toronto Master Gardeners Garden Guide: Toronto is the epicentre of a North American infestation of the box tree moth, Cydalima perspectalis (Walker). The arrival of this invasive pest was officially announced by the Canadian Food Inspection Agency in November 2018.

The moth crossed into the US at Niagara in the summer of 2021, so the US is still in the very early stages of responding to the infestation. This pest (originally thought to have come from Asia) has now reached plague proportions. They are attacking (and sometimes killing) our pretty and widely-grown evergreen boxwood plants, Buxus spp.

An infested boxwood plant is disfigured by the box tree moth by the loss of leaves, by webbing spun by the larvae, as well as larval excrements. Larvae feed principally on leaves of the host but may also attack the bark. They seem to prefer boxwood plants that receive partial shade but can also be found in full sun gardens.

This long-ish article includes many links to other helpful resources as well as tips on identifying box tree moths, and treating the damage they do.

[Editor’s note: this primer was prepared by Desre Kramer, who in addition to being a member of Toronto Master Gardeners is also my wonderful sister-in-law.]