Zeuzera pyrina was introduced from Europe and North Africa accidentally into the United States and first reported in New Jersey in 1887. It has since increased its range westward and southward. Adult leopard moths are white with numerous black spots on the thorax and wings, and can be up to 1.5 inches long. They can be found approximately from May to September during the growing season. (This varies upon geographic location. In New Hampshire, adults may be most common from early-July through mid-August.) Adults are described as heavy-bodied, weak flyers. Male moths are noted to be strongly attracted to lights. Eggs (light yellow to bright salmon/pink in color) are laid in masses or clusters in bark crevices and females are capable of laying up to 800 eggs in a single season. Larvae bore in through the bark and feed, eventually in the heartwood. Caterpillars may also be referred to as "carpenterworms" because this life stage is found developing in the wood of host plants. Larvae are also capable of relocating to new branches if the one it selects is too small for its full development. Mature caterpillars can be up to 2 inches long, pale yellow in color, with black heads and black dots on the body. Larvae are commonly found in branches as well as the trunk. The life cycle of the leopard moth typically takes two years to complete, with pupation occuring in a larval gallery.
Smaller diameter trees and branches are often most harshly impacted by this insect. In these scenarios, dieback can occur. Frass (large, coarse pellets) may be seen falling from cracks in the bark. Similar species also referred to as carpenterworms (ex. Prionoxystus robiniae) may cause similar damage and symptoms on overlapping hosts. Exit holes from adult moths leaving the host plant can sometimes be found in limbs, with the old pupal case remaining in the hole. Over 125 species of deciduous trees have been recorded as hosts of the leopard moth. Even though this insect is widespread, it historically has not been considered to be an important pest in New England because populations generally remain low. In other countries, it is a significant pest of olives, apples, and pears and there is concern about range shifts of the leopard moth due to climate change (Fekrat and Farashi, 2022).
Look for branch dieback and frass sticking out of deep bark cracks or gallery openings. Check stressed trees first.
Promoting tree vigor with appropriate practices for the host plant, especially adequate watering, can help prevent leopard moth attacks. Prevent mechanical damage to trees, as this may be attractive to the leopard moth and other woodboring insects.
Woodpeckers and certain other bird species are the main predators of the leopard moth. Additional natural enemies of this insect have been noted, including but not limited to: Copidosoma truncatellum (egg parasitoid), Diadegma terebrans (ichneumonid wasp parasitoid), and other parasitoid wasps depending upon geographic location (CABI; Invasive Species Compendium). Natural enemies also include certain species of nematode, such as Steinernema carpocapsae and Steinernema feltiae (CABI; Invasive Species Compendium).
Abamectin (NL)
Acephate (NL)
Azadirachtin (NL)
Bifenthrin (NL)
Chlorantraniliprole (NL)
Chlorpyrifos (N)
Cyantraniliprole (NL)
Emamectin benzoate (L)
Indoxacarb (L)
Permethrin (L)
Spinetoram+sulfoxaflor (N)
Spinosad (NL)
Tebufenozide (NL)
Active ingredients that may be injected include: Abamectin (injection), acephate (injection), and chlorantraniliprole (soil drench).
When used in a nursery setting, chlorpyrifos is for quarantine use only.
Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.
Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.
