Spray or scrape egg masses and watch for treatment program

Spongy moth (Lymantria dispar) eggs are tough! They can survive temperatures as low as –20°F.

You can continue to spray egg masses with Golden Pest Spray Oil when the temperature is over 40°F. The oil kills the eggs, reducing the population of spongy moth next spring.  This spray oil is available to purchase online or at some garden centers and retailers.  If you have many egg masses, consider adding food coloring to your spray oil so you can see which egg masses you’ve already treated.  Although more difficult, and you must be careful not to damage the bark of the tree, you can also scrape egg masses into a container and cover them with soapy water for 2 days.  You may then discard eggs in the trash. Don’t leave any part of the egg mass attached and don’t allow it to fall onto the ground, they will survive to hatch next spring!

Spraying spongy moth egg masses with an approved horticultural oil
Photo Credits: Bill McNee WI DNR.