By Troy Kimoto, Canadian Food Inspection Agency


The Asian gypsy moth (AGM) (Lymantria dispar asiatica or L. dispar japonica) is an invasive pest present in China, Russia, Korea and Japan (Figure 1). This polyphagous insect is not known to occur in Canada and poses a significant threat to Canada’s forests, biodiversity and economy. The larval stages (i.e. caterpillars) (Figure 2) feed on the leaves of many economically important trees such as oak, larch, birch, alder, hazelnut, apple, cherry, pear, poplar, willow, pine and spruce. Caterpillars can consume the entire leaf and under high populations, this insect can strip all the leaves from a tree leading to reduced growth and in the event of multiple years of defoliation, tree mortality.
Female moths lay egg masses (Figure 3, 4) on host trees as well as man-made structures. This behavior allows this moth to hitch-hike to new areas – thus the term gypsy moth.

Pathways Into Canada

As with many moths that are nocturnal, female AGM are attracted and fly towards lights. When containerized consignments (e.g. iPads, running shoes, granite, food, etc.) are loaded onto ships and cargos in Asia, female moths can lay egg masses on them or their content. If the egg masses arrive in Canada during the hatching period, the larvae will disperse with the wind over long distances, thereby increasing the likelihood of finding a host tree. If enough individuals successfully develop to the moth stage, a population could become established.

What Can You Do to Help?

As AGM feeds on a wide range of hardwood and coniferous trees, its introduction into Canada would likely impact municipal street trees and natural areas as well as many industries. Therefore, early detection of this pest, if introduced into Canada is crucial. This is why the Canadian Food Inspection Agency has put in place a surveillance program and developed outreach tools for this pest.

If you see suspect egg masses or adult moths, please contact your local CFIA office. AGM is regulated by the CFIA. To find out more about this insect, visit the CFIA website.

Figure 1. Female Asian gypsy moth. Note black crescent pointing to the dot on the wing.

Figure 2. Asian gypsy moth larva. Note the 5 pairs of blue bumps followed by 6 pairs of red bumps.

Figure 3. Female moth laying an egg mass.

Figure 4. Egg mass on vessel from Asia.

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