Richmond Hill combating invasive European gypsy moth and you can help

Thestar.com
May 3, 2021

Richmond Hill is taking on a fight with the European gypsy moth and residents are encouraged to monitor their trees to identify any signs of infestation.

WHAT IS THE EUROPEAN GYPSY MOTH?

The European gypsy moth (Lymantria dispar dispar) is a naturalized invasive insect found throughout southern Ontario, including parts of Richmond Hill.

Gypsy moth caterpillars eat the leaves of a variety of tree species such as oak, birch and maple, causing the trees to lose some, or in extreme cases, all of their canopy. However, since the canopy has the ability to regrow as the season progresses, long-term effects can be reduced or prevented through management techniques.

Infestation levels in Richmond Hill have been low since the early 1990s; however, recent observations have identified a re-emergence in 2020-21.

WHAT CAN YOU DO TO MANAGE TREES ON YOUR PROPERTY?

Residents are encouraged to monitor the trees on their property to identify any signs of infestation and take action to remove gypsy moth.

From now until early May, check the trunk and/or underneath branches for light brown, felt-like gypsy moth egg masses and remove them before they hatch into caterpillars.

If the egg masses are very high up on the tree, you may need to consult with a certified arborist.

Remove the egg masses by gently scraping them into a container with a dull knife, soak them in soapy water for 48 hours before bagging them and throwing them in the garbage.

If the eggs have already hatched, the caterpillars can be picked off by hand or trapped by placing burlap around the trunk. The burlap provides a cool place to hide from the midday heat and will prevent the caterpillars from crawling back up the tree to feed on the leaves.

Pick off or scrape the trapped caterpillars into a container of soapy water, let soak for 48 hours before bagging them and throwing them in the garbage. Wearing gloves while handling the caterpillars is advisable to avoid any skin irritations or reactions.

Learn how to make a burlap trap at RichmondHill.ca/GypsyMoth.

Trees that have lost their leaves should be watered regularly to promote leaf growth. Extensive watering should occur during the hot summer months when natural precipitation is low and most caterpillars have completed their feeding cycle and trees are stressed.

WHAT IS THE CITY DOING FOR TREES ON PUBLIC PROPERTY?

Richmond Hill is using a number of different techniques to minimize damage to trees on city property and help reduce the spread of gypsy moth in our community. This includes egg mass removal, pesticide treatment, watering and monitoring. The city also consults with York Region on how to manage this insect.

City staff are removing egg masses on small- to medium-sized trees using a portable vacuum and through manual scraping to reduce the number of hatched caterpillars in the spring.

To date, city staff have removed a total of 65,281 gypsy moth egg masses from trees on public property, including 53,386 egg masses removed from 4,328 street trees and 11,895 egg masses removed from trees in 44 parks.

In late April, select trees will be treated with pesticide (TreeAzin™) which is injected into the trunk of the tree to help minimize damage caused by gypsy moth.

Watering will occur in the hotter summer months if necessary.

For more information, visit RichmondHill.ca/GypsyMoth.