Have you noticed spongy moth egg masses in your neighborhood? Last year was a boom year for spongy moth (formerly known as gypsy moth) caterpillar populations, especially in Central and Western NY. Egg masses contain 600-700 eggs each and will hatch around May. If you find them now, you can scrape them off trees or buildings and drop them into a container of detergent to prevent the eggs from hatching.
Spongy moths are non-native, but are naturalized, meaning they will always be around in our forests. They tend to spike in numbers roughly every 10-15 years but outbreaks are usually ended by natural causes such as predators and disease. Removing their egg masses is not a cure for spongy moth infestations, but it is a small step you can take to help protect trees in your neighborhood. To learn more about this species and management efforts throughout the year, visit our website.
Pictured: spongy moth egg masses on a tree
are there certain species of trees that they prefer?
They are happy with most hardwoods, but will eat pine needles if it is convenient. They don’t mess much with bushes – mostly trees. Same with the egg cases – they tend to lay their eggs on the tree they want the caterpillars to eat.
Can you spray a detergent solution directly on the eggs on the tree?
You can, but the recommended solution is Neem oil or horticultural oil as it smothers the eggs and is relatively harmless to the environment. Physically removing the eggs and killing them is the best method, but it is easy to leave some behind. Some people do both.
Many masses are too high to reach easily. I find if I pump up my sprayer I can usually shoot at least 10′ up the tree. They also are not always on the trunk – they can be found on many of the lower branches, and even objects/buildings that looked attractive to the moths. Once you get keyed-in to what they look like they are pretty easy to spot. Just don’t be duped into thinking you can destroy them all!
Another issue is that these moths do not recognize property lines. If possible, get your neighbors outdoors killing the eggs as well. While it is obviously folly to believe we can control them, if we can at least reduce the STRESS on our trees it can cut down on mortality and disease.
If I only scrape them off the tree , does this result in them dying or am I wasting my time. (When I am out hiking, I dont carry detergent)
If you just scrape them off of the tree to the ground, a good many could live – and they are right under their food source. Likely many will die or be eaten by insects or other predators, but the the idea of a bucket is to get them away from the intended host tree in case they do hatch. You could just as easily scrape them into a baggie and throw them in the trash when you get home. Just make sure you empty your trash!
But if you are out hiking, you are likely wasting your time trying to scrape any off. Killing all the a fraction of the eggs along a trail is not likely to amount to much. Perhaps they are good on crackers.
Any updates for Warren country NY?