Box Tree Moth

Remember all those black-headed green caterpillars feeding on the leaves of your boxwoods last year?  These are Box Tree Moth (Cydalima perspectalis) larvae and reports from the Greater Toronto Area indicate that this pest is still very active in the GTA.  Thankfully, biological insecticides are registered to suppress populations of larvae. Larval treatments in spring and summer can help keep your boxwoods looking healthy and full.

Larvae overwinter in webby tents, called “hibernaria”, becoming active on foliage during mild spring days in late April and May.  Box tree moth larvae are green with black heads and black spots and stripes on their body. (Slide the arrow over to see the exposed larva in the image above)

Boxwood moth larvae
Feeding damage from young box tree moth larvae

As days become warmer in May, larvae will feed by chewing the surface of leaves and building their strength as they molt into larger larval sizes (known as “instars”).

As larvae mature, they develop larger mouthparts and can consume entire sections of leaves. Webbing and frass pellets are another sure sign of box tree moth.

A second generation of larvae hatch in summer and can be found feeding on boxwood up until mid-September. 

Heavy feeding damage and lots of webbing from box tree moth larvae.

Thankfully, actively feeding larvae can be treated with biological insecticides, but early detection is key to success. Inspect your boxwood plants for this pest by pulling apart twigs and looking for webbing, frass pellets and actively feeding larvae.  

Biological insecticides are registered to suppress populations of larvae in Ontario.

Call Green Bird Horticultural Ltd. today at 647-882-8500 for a free estimate to treat your boxwood and protect them against defoliation from this invasive pest.

We also treat for LDD Moth (formerly Gypsy Moth) an invasive pest and important defoliator of several species of trees and shrubs in our area.