LDD Lowdown

Two people using binoculars to look up into the trees

LDD moth (formerly gypsy moth) has a new name: spongy moth. We continue to use the name LDD moth in this article, but we’ll use the new name (spongy moth) moving forward.

Managing LDD moth

Over the last two years, southern Ontario has witnessed an LDD moth outbreak, and our watershed was no exception. Hundreds of invasive Lymantria dispar dispar caterpillars were seen eating the leaves of oak and other local trees like maple, birch and poplar. With each caterpillar eating up to one square metre of leaf material before cocooning, they left many trees looking bare.

Although healthy trees can withstand LDD moth infestations, repeated infestations can weaken, damage or even kill trees. The good news for 2022 is that natural control methods are starting to take effect. CVC monitoring staff reported seeing an increase in the presence of parasitic insects, Entomophaga maimaiga fungus, egg mass predation (from birds, mice and other small mammals) and nuclear polyhedrosis virus (NPV), a virus that’s harmless to humans but lethal to LDD moths. All of these factors work together to control LDD moth, and it’s expected that LDD moth populations will begin to decline.

Not out of the trees yet

It’s still important to take proactive measures on your property to prevent LDD moth damage. Early spring is a good time to identify and remove egg masses before caterpillars emerge in late April to early May.
Parasitic wasp pupae beside LDD moth egg masses
Scrape the oval-shaped, tan-coloured egg masses off tree trunks and other surfaces like decks or house siding into a container. Fill the container with soapy water. Stir the egg masses and break them up if possible. Seal the container and let it sit for two days to kill the eggs and then put them in the garbage. Scraping egg masses onto the ground will not kill them.

Wear protective clothing as contact with caterpillars and egg masses can cause irritation or allergic reactions in some people.

Parasitic wasp pupae near LDD moth egg masses.

Helpful resources

Save the date

Local conservation authorities will be hosting a free webinar to provide an update on the status of LDD moth in the area. The webinar will take place the evening of Wednesday, April 20. Registration will be available at cvc.ca/events so check back soon.

Scroll to Top