Getting rid of Gypsy Moths

Getting rid of Gypsy Moths Ontario

This post will tell you everything you need to know about getting rid of gypsy moths, this non-native insect that can cause huge destruction to trees in our area.

Affected Trees: Broadleaf trees, including oaks, maples, poplars and birches

Gypsy Moth Ontario

Gypsy moths, otherwise known as spongy moths (Lymantria dispar), pose a significant threat to trees in Ontario, impacting a broad range of tree species. The gypsy moth is a non-native insect that defoliates trees. Outbreaks of spongy/gypsy moths tend to be cyclical, occurring every five to ten years. The last major outbreak in Ontario was a multi year outbreak beginning in 2018 and continuing until 2021. According to the Toronto and Region Conservation Authority the population has now declined, with no major outbreaks of Gypsy Moth reported since. 

Getting rid of Gypsy Moths

Getting rid of Gypsy Moths – where are they and why do we need to do it?

There is no room for complacency when it comes to the Gypsy or Spongy moth. If gypsy moths take up residence in your trees, they will cause a lot of damage and, if left undisturbed, could eventually kill them. 

 

Gypsy moths are found throughout southern Canada. There are populations in southern Ontario, New Brunswick, Nova Scotia, and British Columbia. Whilst there has not been a major outbreak in Toronto since 2021, scientists predict that climate change will increase the frequency and intensity of cyclical outbreaks.

.

Potential distribution of the gypsy moth in Canada based on its probability of establishment as a function of climate. Prepared by applying the output of the Canadian

Potential distribution of the gypsy moth in Canada based on its probability of establishment as a function of climate. 

What trees do gypsy moths eat?

Getting rid of Gypsy Moths Oak

Spongy or gypsy moth larvae can feed on more than 300 species of trees and woody shrubs. However, they prefer deciduous hardwoods. The species of trees most susceptible to Spongy or Gypsy moth infestations in our area are oaks. They also like maples, birches, poplars, and other hardwood trees.

As the larvae grow, they will feed and live on an increased range of preferred host trees and can even include conifers such as white pine or spruces. Conifers fare particularly badly from a gypsy moth infestation and may not survive one year’s infestation. Some species of trees, such as red maple, are not suitable hosts for spongy or gypsy moths and survive an outbreak without defoliation.

Are your trees safe from pests and tree diseases in your area?

Invasive species such as the Emerald Ash Borer threaten our trees in Toronto and the surrounding regions. Do you know how to protect your trees?

Arborist York Region

Worried about the health of trees on your property in Toronto and the surrounding area?

Call Sarginson’s Tree Services now (905) 391-8454

How do gypsy moths kill trees?

Getting rid of the Gypsy Moth

Spongy moth or gypsy moth larvae are voracious feeders. During the larval stage of its life cycle, one gypsy moth caterpillar can eat one square meter of leaves by itself. Bear in mind that one female gypsy moth can produce an egg mass that produces 1000 caterpillars, and you can see the scale of the problem for your trees if you have an infestation.

Gypsy moths feeding weakens and stresses trees, making them more susceptible to diseases and other environmental stressors. 

Whilst an infestation of one year might not be enough to kill your tree, prolonged infestations of gypsy moths will reduce their overall health and longevity. Regular severe infestations cause widespread defoliation of affected trees and their eventual death.

How do gypsy moths affect the environment?

The impact of Gypsy moth infestations on forests and ecosystems can be significant, as defoliation caused by the larvae can weaken trees and make them more susceptible to other stressors, such as diseases and extreme weather events.

In Ontario, aerial photography in 2020 showed the gypsy moth had defoliated 586,385 hectares of forestry. 

The preference of gypsy moths for oaks has a big impact on forest wildlife, especially animals such as deer that feed on oak acorns for the nutrition needed to survive our harsh winters.

Signs of Gypsy Moths? Contact Sarginson’s

Signs of a Spongy or Gypsy Moth Infestation

Early Signs

Defoliation is often the first noticeable symptom. Gypsy moth larvae are voracious eaters and can quickly strip trees of their leaves. Regularly inspect tree leaves for early signs of feeding damage, including small holes, notches, or irregular patterns.

You may notice silken threads hanging from branches and nearby structures which are produced by moth larvae. 

Gypsy moths lay distinctive egg masses containing hundreds of eggs between late Summer and Spring. Egg masses can be found on just about all surfaces but gypsy moths prefer sheltered, flat places to lay them. Look for egg masses from late summer through to May on tree trunks, branches, or nearby surfaces of buildings, fences, hard landscaping or patio furniture. Egg masses may be high up in trees. 

Gypsy moth damage

What do gypsy moth eggs look like?

Spongy or Gypsy moth egg masses are fuzzy and buff colored and about the size of a loonie. With more serious infestations they could be larger and in clumps. Each egg mass can contain up to 1000 eggs. Later Signs of spongy or gypsy moth infestations

Increasing patterns of leaf loss and defoliation may signal a worsening Gypsy moth infestation. In severe infestations, trees may experience complete defoliation, leaving them vulnerable to stress and secondary pests.

As the larvae grow, they become more noticeable on tree trunks and branches. Large populations can be a clear sign of an advancing infestation.

Observe trees for signs of stress, such as wilting, cankers, or increased susceptibility to other pests or diseases.

Getting rid of Gypsy Moths

Gypsy moth life cycle Ontario

The Gypsy moth life cycle consists of four distinct stages: egg, larva, pupa, and adult.

When do gypsy moths lay eggs?

The life cycle begins in late summer when female Gypsy moths lay their eggs. The egg masses are laid on tree trunks, branches, and other surfaces, often hidden from plain view. These egg masses are covered with protective hairs and scales, providing insulation and safeguarding the eggs from the harsh Canadian winter. The eggs remain dormant throughout fall and winter, awaiting the arrival of spring.

When do gypsy moths hatch? 

With the onset of warmer temperatures in spring, the Gypsy moth eggs begin to hatch. This marks the beginning of the larval stage, during which the tiny caterpillars emerge and start feeding on the foliage of their host trees. The larvae undergo several molts as they grow, shedding their old exoskeletons to accommodate their increasing size. This stage typically lasts for about 6 to 8 weeks, depending on environmental conditions and the availability of food.

Getting rid of Gypsy Moths Ontario

Gypsy moth Pupae

As summer approaches, the fully grown Gypsy moth larvae enter the pupal stage. The pupa is a non-feeding, transformative stage where the caterpillar undergoes a metamorphosis within a protective cocoon. This process typically takes a couple of weeks, and during this time, the physical characteristics of the caterpillar undergo significant changes and they will eventually emerge as adults. 

Gypsy moths emerge as adults 

By mid-summer, the adult Gypsy moths emerge from their pupal cases. The males are generally smaller and have feathery antennae, while the females are larger and possess broader, less feathery antennae. Once emerged, the primary goal of the adult moths is to reproduce. The females release pheromones, chemical signals that attract males for mating. After mating, the females lay a new batch of eggs on tree surfaces, restarting the life cycle.

How to stop the spread of gypsy moths?

The best defense against moth infestations is to keep your trees healthy and promote vigor with a regular pruning and tree maintenance regime. The gypsy moth will attack a damaged or stressed tree first. These trees often have wounds in the bark that provide a protective environment for the eggs and larvae with a shelter that aids in their survival.

Getting rid of Gypsy Moths Ontario

Getting rid of gypsy moths

You can remove egg masses at any time from when they appear from late Summer before they hatch in the Spring. However it might be most efficient to handpick and destroy Gypsy moth egg masses during the winter to reduce the number of hatching larvae in the spring. 

Place a container below the egg mass you have spotted and scrape the mass from the surface with a flat scraper. Make sure you haven’t left any eggs in crevices in the bark or surface they are laid on. Put the egg masses into a bucket of soapy water and leave for two days to kill the eggs. 

Guide to Removing Gypsy Moth Eggs from your Trees

Getting rid of Gypsy Moths

How to get rid of gypsy moth larvae

In Spring, watch for leaf damage and other signs of larvae as the eggs hatch and begin feeding on the foliage. 

In April or May, use a biological insecticide such as Bacillus thuringiensis (Bt), a naturally occurring bacterium. This targets Gypsy moth caterpillars without harming other plants or insects. 

From May onwards use burlap bands to trap the caterpillars and then destroy them. From June to July you can remove pupae by hand.

Despite it being labor intensive it is better to deal with gypsy moth infestations by hand and natural measures rather than using pesticides, which are in any case, only effective in the very early stages. 

Sarginson's Tree Services Ontario