Species Spotlight: Spongy Moth and Wood Frog

March 21, 2022

Defoliation in the Adirondacks as a result of the Spongy Moth infestation. Witnessed in 2021.

Spongy Moth; Lymantria dispar dispar

Spongy moth caterpillars by Marque Moffett, 2021

by Cara Gentry

During the summer of 2021, our Coordinator of Land Stewardship, Cara Gentry, went mountain biking in the Adirondacks and observed areas that had been completely defoliated by a boom in the population of Spongy Moth caterpillars. Formally referred to as the Gypsy Moth, the species was officially renamed recently due to its former name having derogatory implications. The voracious appetites of these caterpillars lead to the trails being carpeted green with fallen pine needles and an unexpected sunburn as the usually dense canopy was gone.  

The Spongy Moth is a nonnative invasive species in North America known for perpetuating the defoliation of many native trees and plants. The Spongy Moth found its way to North America over one hundred years ago when the caterpillars were brought to the US to study new sources of silk production. The moths soon found their way to suitable environments throughout the northeast and have now spread as far south as North Carolina and as far west as Minnesota. In the state of New York, Spongy Moth caterpillars are easily able to find suitable habitats for breeding and feeding. Maple, pine, apple, and specifically, oak trees are all preferred plant species for the Spongy Moth to feed on. In the forests of New York, Spongy Moth populations tend to rise in fall in trends stretching over 10-15 years. Outbreaks that occur during these cycles can cause thousands of acres of damaged forests and for around 20% of the trees moths come in contact with to die. The 2021 population spike in the Adirondacks led local resident, mountain biker, and chemistry instructor, Marque Moffett to say “The forests were so strange. To see them so stripped down in the middle of the summer was really sad. Rather than the lush green we’re used to, it felt like the last barren days of fall before the snow falls. Only hotter. And with poop rain”. 

A droplet of “poop rain”. Courtesy M. Moffett

Spongy moth caterpillars attached to a barrier band, dec.ny.gov

Knowing how to identify the Spongy Moth can help prevent the defoliation of New York’s plant population. Spongy Moths begin their life cycle as caterpillars which hatch from eggs in the months leading up to summer. The eggs from which the caterpillars hatch are a light tan color that is surrounded by a hair-like coating which looks rather sponge-like, leading to their new common name.  Most often, the egg masses are usually found on tree trunks but can be found on a number of other outdoor surfaces. Once hatched, the caterpillars begin feeding on vegetation and eventually can grow up to 2.5 inches long. Spongy Moth caterpillars are identified by a series of blue and red dots running down their backs as well as hair growth across their bodies. Cara pointed out that the huge population of the caterpillars in the forest canopy along with their seemingly limitless appetite lead to the rather disturbing realization that the constant pelting on her mountain bike helmet and body from above was in fact caterpillar poop falling from the rapidly diminishing forest canopy. 

Beginning in June and early July, caterpillars begin pupation and emerge as fully grown moths. Once hatched, the male moths begin searching for a female mate. Despite having wings, female Spongy Moths do not fly due to the heaviness of their own body weight. Identifying the difference between the two is simple, first since only males will be seen flying. Male Spongy Moths are categorized by their brown hue and coating of black spots across their wings. Females have a white body with a brown strip shaped like an upside down V pointed towards their head. Adult Spongy Moths are of no direct threat to forest vegetation since it is only the caterpillars that feed. 

Adult spongy moths with their eggs, NYS DEC dec.ny.gov

With the knowledge to identify the Spongy Moth, its caterpillars, and egg masses, the issue now becomes controlling the species and preventing defoliation. There are many ways to prevent Spongy Moth caterpillars from damaging trees starting with identification of egg masses. It is important to act during the spring months to prevent Spongy Moth caterpillars as it is during this time they begin to hatch from their eggs. If egg masses are spotted on trees, simply removing them from the tree and placing them in a container can mitigate potential damage. Applying an adhesive band, called a barrier band, around trees identified to have Spongy Moth eggs is a simple method of trapping the caterpillars as they hatch and begin searching for leaves to consume. More information on how to catch the Spongy Moth can be found on the NYS DEC website. 


While this past year we did not see a huge population of Spongy Moth deforestation on and WVLT properties, there are a lot of egg masses visible on trees in the area just a little farther north. We will continue to keep our eye out for egg masses on our properties and help to remove the eggs before they can hatch.

P.S. We did write about Spongy Moths once before – but thought that given the recent name change it would be pertinent to cover them again. To read the original article click here!


Wood Frog; (Rana sylvatica) 

by Adam Winne & Cara Gentry

Wood Frog on WVRT by Cara Gentry

As February ends, the air temperature warms, the snow begins to melt, and it quickly becomes amphibian migration season in the Hudson Valley. 

One of the most common amphibians to see during the spring migration is a wood frog. You can identify them by several traits, they are normally found in a range of shades from light tan to a dark brown, however are sometimes found to have hues of gray and tan. While their complexions may differ, the wood frog is easily distinguished by a dark streak behind each eye, often earning the title of a “robber’s mask”.  Wood frogs are normally spanning from 1.5-2.5 inches in length, with females often being larger than males. Wood frogs are incredibly common across North American, as they are adaptable to varying weather events common in the region.  

Adult male wood frog, James Harding animaldiversity.org

Around this time of year, wood frogs will migrate from their winter forest homes to vernal pools in order to find a mate and reproduce. Vernal pools are isolated wetland features that cycle through being wet and dry, often on an annual basis. These pools are ideal breeding grounds for the wood frog, and are an essential feature in the life cycle of the wood frog. Wood frogs are viewed as an indicator species of vernal pools, since they are fully dependent on these pools and can be easily found when encountering one of these wetland features. Female wood frogs lay eggs in vernal pools and can lay anywhere from 1,000 to 3,000 eggs during mating season, forming an egg mass that can grow up to 4 inches in diameter. Once hatched, each tadpole begins feeding on the nutrient-filled egg from which they grew. Wood frog tadpoles need to eat and grow once they are born in order to reach metamorphosis before their vernal pool dries. 

Wood frog egg mass, Orianne Society oriannesociety.org

Wood frogs begin their migration to vernal pools in March and April, when the ground has thawed and night temperatures remain over 40°F. The trek made by wood frogs to vernal pools does not come without its challenges, as many wood frogs must cross roads in order to complete their journeys. Luckily for the wood frog, many volunteer-based initiatives have been created in order to ensure migrating amphibians can safely cross roads. The NYSDEC Amphibian Migration and Road Crossings Project partners with many organizations, including the Wallkill Valley Land Trust, to sponsor events during March and April to help migrating amphibians successfully reach vernal pools. As a WVLT intern, I recently had the pleasure of joining WVLT for a night of helping and counting wood frogs migrating to vernal pools and had a great time helping a few frogs across the street in early March. Despite it being my first time looking for wood frogs, they were very easy to identify and I am excited for more amphibian migration events in the future. If you wish to get involved helping the Wallkill Valley Land Trust with amphibian migrations, you can sign up to volunteer at https://wallkillvalleylt.org/volunteer/

You can find out more about the Amphibian Migration and Road Crossings project, vernal pools, wood frogs, and other Hudson Valley amphibian species  by visiting the AM&RC webpage at https://www.dec.ny.gov/lands/51925.html

Spongy Moth Resources






Wood Frog References

Kenney, Leo P., and Matthew R. Burne. A Field Guide to the Animals of Vernal Pools. Massachusetts Division of Fisheries & Wildlife, Natural Heritage & Endangered Species Program, 2009. 





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