Gypsy moth egg masses are fuzzy, tan in colour, and range in size from a dime to larger than a toonie. Egg masses can be laid on just about all surfaces but prefer sheltered, flat areas such as the underside of tree branches, the crevices of fences, patio furniture, and landscaping rocks.

It was first detected in Ontario in 1969 and has quickly spread across southern Ontario over the next decade. Where are they found? Pockets of gypsy moth infestation flare up periodically within these counties. Defoliation of the tree canopy in many areas across Ontario has been observed widely this year. These natural biological controls contribute the most to keeping levels within a normal range and tend to follow 2-3 years after the gypsy moth populations peak. In North America, the species is well established in the Northeastern US and adjacent areas of Canada.

The gypsy moth has over 300 known host plant species. These outbreaks may range from a single woodlot to thousands of acres. The species is a generalist and readily consumes hundreds of plant species causing defoliation and occasionally host death. Continued defoliation of trees can lead to their decline and eventual death.
150 of which are preferred hosts. Some of its favoured host tree species include oak, maple, birch, alder and hawthorne. Local communities or individual property owners may choose to spray to suppress these outbreaks, but DATCP generally does not treat in these areas. The Gypsy Moth is a moth species native to Europe and Asia and considered a problematic and invasive species across its introduced range.

The larvae (caterpillars) feed on foliage of a wide range of hardwood and some softwood trees. The egg masses are laid individually or in large clumps. The Gypsy Moth Life Stage model (GLS) has been used to predict the invasive range of the European gypsy moth in North America and New Zealand. The European Gypsy Moth (Lymantria dispar dispar) is an invasive forest pest that was introduced accidentally in the United States in 1869.Since then, the Gypsy Moth has expanded its range over much of the eastern United States and Canada.


The gypsy moth virus disease is often referred to as “wilt” because dead caterpillars hang in an inverted “V” from tree trunks or foliage. The European Gypsy Moth is a major forest pest concern because the caterpillar, or larva stage of the insect, eats the leaves of trees, defoliating them which makes them more susceptible to disease and damage from other insects, like tent caterpillars. The GLS has also been used to model the invasive range of Asian subspecies, despite observed differences between the European and Asian populations.