More specifically two types of caterpillars that can cause huge problems with your trees and boxwoods. I am speaking of Gypsy Moth, now know as Sponge moth and Boxwood Tree Moth.
Both of these pests are present in Southern Ontario at this time. As a home owner Boxwood Tree Moth is an easier pest to control than Gypsy Moth is . Having 3- 5 lifecycles a year and feeding on Boxwood in your garden.
A green and black caterpillar with a voracious appetite that can defoliate your boxwood in one year making it not only unsightly but very difficult to recover from. You might notice an adult moth flying around, or perhaps notice webbing, frass(poop) or leaf defoliation on your boxwood.
Pruning the caterpillars out of the boxwood when you notice them and bagging both the clippings and the pests to prevent them from moving on is one method. Another safe and reliable method is using BT or BTK available at hardware stores but in short supply (stock up!). This is a naturally occurring bacteria and safe to use for your plants and around your pets and kids applied by you with a pressurized sprayer. Making sure you completely saturated all boxwoods on your property. Note, let neighbours know that this pest is close by. If the neighbours boxwood harbours these caterpillars, yours will once again become infested. Spring applications of BT are more helpful than those applied later in the season. Though Spring to fall coverage may be necessary in your area. What happens to the caterpillar is that they injest the BT and their tummies expand and burst. Too much of a good thing!
So why use boxwood if they have a significant pest? Good question. Those who love boxwood, couldn't imagine their landscape without them. They are a gorgeous emerald green evergreen that comes in many shapes. Hedges, cones, spheres, the possibility is endless. I recently added 40 Graham Blandy Boxwood to a clients landscape that when planted were 42". A perfect screen to hide an air conditioner unit, generator or to soften a new patio edges!