Controlling LDD Moth in Richmond Hill

The LDD moth (also known as Gypsy Moth) outbreak that has impacted most Central Ontario communities has been a significant problem for Richmond Hill as well. Our staff have taken steps to mitigate this impact and Council passed a staff report this month to take further measures. To view the full staff report visit
Some facts about LDD moth
·         LDD moth caterpillars eat the leaves of a variety of tree species such as oak, birch and maple.
·         The caterpillars tend to only feed and damage trees for a short period from June until mid-July.
·         The risk of trees dying is extremely low. Most healthy trees will regrow their leaves as the season progresses.
·         LDD moth outbreaks happen in cycles every 7 to 10 years and each outbreak can last a few years.
What the City is doing for trees on public property
In anticipation of the impact LDD moth would have this year on our urban tree canopy, the City employed a number of different techniques to minimize damage to trees on City property and help reduce the spread in our community. 
·         This winter, City staff removed more than 65,000 egg masses on small to medium sized street and park trees using a portable vacuum and through manual scraping to reduce the number of hatched caterpillars in the spring. 
·         Watering will occur when heavy defoliation is seen on street trees until they have regrown their leaves in August.
The City will not be spraying pesticide
·         Spraying pesticide is costly, time sensitive and not feasible for a large spread out area such as a city
·         It is non-selective, which means it will kill all caterpillars, not just LDD moth. This also has negative impacts on birds that feed on caterpillars.
·         Caterpillars still need to ingest the leaves in order for the pesticide to work, so trees will still suffer defoliation and there will still be caterpillars around for some time as it is not 100 % effective.
What residents can do for trees on their property
·         Residents can reduce the impacts of LDD moth caterpillars on their property by applying burlap traps and/or sticky barrier bands to the trunks of infested trees. This gives the caterpillars a place to hide from the midday heat and makes them easier to remove. Once removed from the tree, place the caterpillars into a container of soapy water, let soak for 48 hours before bagging them and throwing them in the garbage.
·         Trees should be watered regularly to promote leaf growth. Extensive watering should occur in the mornings and evenings during the hot summer months when natural precipitation is low.
For more information, visit