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Gypsy Moth in Caledon

Posted on Monday August 26, 2019

There have been a number of Gypsy Moth reports in Caledon this summer. Here are a few things that you need to keep in mind.


If Gypsy Moth is reported on Town property, please contact Service Caledon - 905.584.2272 x. 7750 or It will be investigated by Town arborist staff. They will typically survey the area for egg masses and decide what to do based on the severity of the infestation, level of defoliation, tree health, tree species and available resources.

Tree health and species are important factors. Generally healthy trees can survive Gypsy Moth. Defoliation from the larva feeding on leaves stops early summer and the moths are short lived. Infestations seem to occur in cycles so while there may be an infestation one year, it does not mean it will continue year after year.

Town of Caledon and provincial by-laws discourage pesticide use and staff would not engage in mass application of pesticides without Council direction and approved resources. The Town does not provide any resources for private property. Private property owners would need to consult with their chosen tree care professional to determine the best way to manage their own property.


What is the Gypsy Moth?

The European Gypsy Moth is considered to be a major pest in North America. In the caterpillar or larval stage, the insect eats the leaves of trees making them more susceptible to disease and damage from other insects.

How much damage can the Gypsy Moth cause to trees?

Depending on the level of infestation, damage can range from light to almost complete defoliation or loss of leaves. In some situations, if the tree has been weakened or stressed by other conditions, the tree may die.

What kinds of trees are most affected by the Gypsy Moth caterpillar?

Gypsy Moths prefer oak trees but will eat all kinds of hardwoods including elm, birch, poplar and willow trees. In some rare cases, when the number of Gypsy Moth is extremely high, the caterpillar will feed on evergreens such as pine and spruce. They do not appear to like sycamore, butternut, black walnut, dogwood or balsam fir.

What is the lifecycle of the Gypsy Moth?

The moths are short-lived and seen in mid-summer. Both genders die after the female lays its eggs on the limbs and trunks of trees, on rocks, buildings or in other sheltered areas. The egg masses remain in place all winter and hatch the following spring from late April to mid-May. Once hatched, the caterpillars begin to feed for approximately seven weeks.

Are there any natural predators to the Gypsy Moth?

Yes. Predators include other insects like wasps, flies, beetles, ants and spiders and animals such as chipmunks, squirrels and raccoons. When caterpillars first hatch, birds such as chickadees, blue jays, robins and nuthatches will prey on them. Gypsy Moth populations are also reduced by diseases caused by bacteria, fungi and viruses.



For questions or inquiries, please contact Service Caledon: 905-584-2272 x 7750

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