Another Year of Invasive Moths

Another Year of Invasive Moths

If you have trees on your property, you’re likely familiar with the invasive LDD moth (also known as gypsy moth*). This time of year, we start to see a lot of LDD moth caterpillars emerge from their egg masses.

We’re currently in the third year of a population boom for these invasive forest pests and it’s shaping up to be another year of hungry caterpillars. The Ministry of Natural Resources and Forestry (MNRF) has forecasted that we can expect severe defoliation. Learn more about MNRF’s forecast and other related information.

Young caterpillars emerge from two egg masses. You can also see a pupa from where an adult moth emerged.

How to protect your trees:

There are a few steps you can take to protect your trees and shrubs:

  • Scrape egg masses off into soap water.
  • Wrap tree trunks with double-sided sticky tape to catch caterpillars.
  • As caterpillars grow, wrap a wide strip of folded burlap to create a place for caterpillars to hide. Monitor the burlap and remove caterpillars.

Watch this video from the City of Grand Rapids to learn how to wrap a tree with sticky tape.

Watch this video from the City of Toronto for more information on how to wrap burlap.

In forests, LDD moths rarely cause large-scale damage and management programs are expensive. There is a role for insect outbreaks in forest ecology. They create habitat for wildlife that use tree cavities and eat decaying trees, such as woodpeckers and the insects they feed on. Small gaps in the forest caused by a few dead trees can also make room for new plants and trees to grow.

If you have concerns about LDD moths, consult a local tree service company to assess the impacts of your forest’s health and to determine if action is required. Learn more.

Here’s what CVC is doing:

Credit Valley Conservation is in the process of developing an Invasive Species Strategy that recommends a comprehensive pest management framework to identify our priority invasive species and priority sites for monitoring. We will be developing an LDD moth monitoring program. Once this program is finalized, we’ll begin active management of LDD moths at our conservation areas.

Here’s what partner municipalities are doing for their public spaces and street trees:

  • City of Brampton: using a variety of practices including egg mass scraping, tree band installations, and ground sprays in priority areas. Learn more.
  • City of Mississauga: continuing their integrated pest management through a combination of egg mass scraping, tree injections and ground sprays in priority areas. Learn more.
  • Town of Caledon: completing egg mass scraping and ground sprays in priority areas. Learn more.

Review more information on LDD moth control options and frequently asked questions. If you have specific questions regarding this invasive pest or other invasive species, connect with us at


*In our efforts to lead an inclusive organization, we will be transitioning away from the use of “gypsy moth” and will be using the term “LDD moth”.

By: Freyja Whitten, Program Manager, Terrestrial Restoration

10 Comment
  • Tony Spencer says:

    Here’s what the CVC is doing?
    You’re developing strategies? How does that even begin to help the current region-wide outbreak? OMAFRA has been monitoring these outbreaks for decades. Last year was a record high year in impact across southern Ontario. This 2021 outbreak is already far beyond the scope of individual property owners to deal with and you seem to be sitting on your hands. If you look on Facebook or any community social media, you will see that people are quite rightly frightened and astounded that there is no visible action plan or evident strategy coming from local government or authorities. By the time you develop your strategy, it’s too little and too late.

    • We’re working with our municipal partners and providing ecology and invasive species expertise on a broader watershed-wide approach to the LDD moth outbreak. We’ve developed an invasive species strategy and are taking actions on invasive species in CVC parks. As we wrap up our work on addressing the devasting impacts of the invasive emerald ash borer, we are shifting our focus to LDD moths and other priorities. In order to pinpoint our efforts and ensure effective and efficient use of available resources, we’re creating an integrated pest management framework. First, we need to monitor LDD (and other invasive species) on CVC properties to determine the areas where the impacts are greatest and the best strategies to address them. This planning is important. LDD outbreaks have been ongoing in Ontario since the early eighties and happen every 7 to 10 years. During outbreaks, the scale of the outbreak changes year-to-year based on local weather conditions, such as a warm spring. It is suspected that fewer extremely cold winter days due to climate change can result in greater LDD moth populations in the spring. Planning and monitoring allow us to adapt and be cost-effective in the fight against the many invasive species on our properties including LDD moths.

  • Robert Waldon says:

    Scraping is only an option as far as we (mere mortals) can reach up. Similar with use of BT; we can only get so high. I guess there’s no way we can “vote the little beggars off the island”?!

  • Dale ohara says:

    this information should have been given last year when I first contacted you. You gave no response other than it’s a natural cycle. Too late to send out this information now. And as for your inclusive language, stop worrying about such things and do your job of informing the public in a timely manner. Get Caledon on board. This information should have been sent out in February to all households instead of leaving us to fight this ourselves. Last year was bad. This year is absolutely horrendous! I doubt we will be able to call Caledon green and tourists to our area will not be wanting to walk our trails with caterpillars dropping on them.

  • Rehana Lobo-Colaso says:

    Last year they took over my fruit trees and much more. It looks like they are back this year. I see caterpillars all over my property.
    Any recommendations?
    Thank you.

  • Margaret says:

    A total disaster. I didn’t read it in May and now I have those caterpillars eon all my willow trees, birches, red maple and apple and cherry trees. Holes in leaves. I realized they are around when I saw dozes of them on my red patio umbrella! Too late for anything? Plus how can I reach so high onto the tree branches?! Isn’t there a plan to do like helicopter spraying? Or something else on a wider scale. I read they are disastrous. First time at my place. HELP!!!!

    • Hi Margaret, sorry to hear this. Unfortunately LDD moths are a problem for all landowners this year. We know some people did join together to do aerial sprays earlier this spring, unfortunately it is now too late in the year for this control option. However you can prioritize protecting some of your trees by burlap wrapping the trunks. You can find more information on this and other control methods on our website. Due to the high LDD population this year we are really hoping the virus (a natural control) will start a population crash. Fingers crossed we start to see dead caterpillars due to it in the next month or so.

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