Spongy Moth and Flighted Spongy Moth

Pest Profile

The spongy moth and the flighted spongy moth are pests that voraciously feed on the leaves of trees and shrubs, threatening forests, urban settings, and agricultural tree crops.

The spongy moth is native to Europe, southern Asia, and northern Africa. It was brought to the U.S. for breeding experiments in Massachusetts in the 1860s and accidentally escaped. It has since moved steadily southward and westward, and now occupies the northeastern U.S. from Maine to Virginia and westward to Wisconsin. Spongy moth caterpillars feed on hundreds of plant species and are capable of defoliating trees at an alarming rate. A single spongy moth caterpillar can eat up to one square foot of leaves per day. In the northeastern United States, millions of these caterpillars emerge each spring and devour large swaths of forest and urban foliage. When trees are repeatedly defoliated, they are rendered more susceptible to other pests and diseases, potentially leading to tree death. Dead trees can increase potential for fire and soil erosion. In addition, the hairs on caterpillars are known to cause skin irritations and allergies for some people.

Young caterpillars feed primarily on oaks, aspen, birch, willows and alder, and older caterpillars feed on a broader range of trees including cedar, pine, spruce, and fir. Common California species such as manzanita, western hemlock, Douglas-fir, and live oak are also prone to damage by this pest.

The primary detection method for this invasive pest is through the use of pheromone traps which are strongly attractive to male moths. The detection of a moth in a trap results in the placement of additional traps around the find location. Eradication measures may be undertaken if the additional trapping indicates that a breeding population is present. Female spongy moths cannot fly and often lay eggs on manmade items near the ground such as car or trailer wheel wells and lawn furniture. California introductions are typically the result of persons transporting these infested articles into California from infested areas.

Another moth of concern is the flighted spongy moth which is closely related to the spongy moth. The flighted spongy moth is native to Asia from Russia through China and into Japan. As the name suggests, the main difference between the spongy moth and the flighted spongy moth is that female flighted spongy moths are capable of flight. In addition, flighted spongy caterpillars can defoliate conifers such as pine and spruce at a younger stage. The appearance and life history of the flighted spongy moth is very similar to the spongy moth, and it is detected using the same trap. The flighted spongy moth has been found entering the U.S. on ships and shipping containers but has not become established due to early detection and effective eradication efforts.

More information can be found at your local County Agricultural Commissioner’s Office.