Mid Instar Larva of Box Tree Moth (Cydalima perspectalis) can be found actively feeding on boxwood in some residential gardens. This is the perfect time to spray biological insecticides like Dipel, Xentari. (photo: J. Llewellyn).
Box tree moth larvae can be found actively feeding on some boxwood shrubs in Residential Toronto gardens, mainly in the Etobicoke area. They seem to prefer boxwood plants that receive partial shade but can also be found in full sun gardens.
Carefully examine foliage for signs of webbing and leaves and twigs that are webbed together. (photo J. Llewellyn)Sometimes the larval webbing can be quite subtle (photo: J. Llewellyn)The larval webbing can be difficult to detect. I find having low magnification reading glasses really helps!Carefully pull apart webbed leaves and twigs and look for green larvae with black spots and black heads. This photo shows the posterior end of a BTM larva. (photo: J. Llewellyn). Carefully pull apart webbed leaves and twigs and look for green larvae with black spots and black heads. Look first on the periphery and then deep inside the branches for this camouflaged larva. (photo: J. Llewellyn)
Dipel and Xentari contain a lethal bacteria such that when BTM larvae consume the spray residue on the leaves, they soon stop feeding and expire within a couple of days.
Inspect your clients boxwood for actively feeding BTM larvae and tree boxwood shrubs to prevent the next generation of larvae and slow the spread of this important pest.
Webbing on foliage can also be caused by spiders (see above photo). Webbing alone is never an indicator of box tree moth. (photo: J. Llewellyn)
This is low temperature injury (from frost events mid-May) and winter desiccation on boxwood.
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