The satin moth or white satin moth, Leucoma salicis, was introduced from Europe or Asia and first reported between Boston, MA and Hampton, New Hampshire in 1920. It has since spread throughout New England and additional locations in the US and parts of Canada. This insect is said to overwinter in the third instar (caterpillars pass through seven instars), either individually or in small groups. This occurs in a silken, cocoon-like bag attached to host plant trunks and branches. In the springtime, caterpillars leave their areas of hibernation to feed on nearby leaves. Fully grown caterpillars may be up to 2 inches long. Caterpillars spin a thin cocoon between leaves or between exfoliating or thick bark crevices. Pupae are dark brown/black and often in a thin, loose silken sack. Pupae also sport brightly colored, yellow setae (hairs) that make them quite attractive. Pupation begins by the end of June, and takes approximately 10 days to complete. Shortly thereafter, moths emerge and females lay egg masses covered in a frothy, white material from July – mid-August. Up to 400 eggs may be laid per mass. Eggs hatch sometime in August, and larvae will conduct feeding in August and September.
The caterpillars of this species have a unique color pattern, which helps us distinguish them from others. The dorsal (back) side of the caterpillar is marked with 10-11 white, intersegmental spots as well as paired, red “setal warts”. The sides of the caterpillars are blueish gray. These caterpillars are known to the edges of waterways, woodlands, and forests from Canada to northwestern Connecticut and central New York. One generation occurs per year with mature caterpillars known in May and June. Host plants include aspen, poplar, and willow, the leaves of which are fed upon by the caterpillars of this species.
While caterpillars of this species are not noted to be of particular concern with regard to causing allergic reactions such as dermatitis, they are a type of tussock moth and do possess hairs, so they should not be handled and should be approached with caution particularly by sensitive individuals.
Current season caterpillars skeletonize leaves until early fall or first frost, then move to their winter hibernation location. Foliage of white poplar, willow, and other Salicaceous plants may be fed upon, including shade trees and ornamentals. Occasionally found on aspen and oak. Feeding in the spring occurs on newly developed host plant leaves. Historically, outbreaks of this insect have occurred, although they are not frequently experienced in Massachusetts in recent years. If an outbreak occurs, severe defoliation can weaken trees and mortality is possible, however trees are often able to survive.
The sex pheromone 3Z-cis-6,7-cis-9,10-diepoxyheneicosene (Gries et al., 1997) called leucomalure (Muto and Mori, 2003) is available to capture male satin moths in baited traps. Black light or mercury vapor light traps are also attractive to the moths, that are most active at night. Visual monitoring of susceptible host plants experiencing defoliation is also helpful in scouting for caterpillar activity. Often, annual populations of this insect exist below severely damaging levels and may be observed at the same location annually. For example, in Beartown State Forest (Monterey, MA) a population of white satin moths has been observed on Populus spp. in 2020, 2021, and 2022.
As with spongy moth, sticky bands have been suggested as a possible means of managing the satin moth on individual trees. It is uncertain how effective this will be on an individual host plant at preventing defoliation. It is suggested that they be placed in the tree in the spring, to capture any wandering caterpillars that overwintered. Egg masses may also be manually scraped off tree trunks whenever found.
Many of the native and introduced parasites of the spongy moth (Lymantria dispar) will also kill satin moths (white satin moths). These include the parasitic fly, Compsilura concinnata, and a species of wasp, Eupteromalus peregrinus (Johnson and Lyon, 1991). Pathogens have been reported as able to kill the satin moth, including but not limited to: a multicapsid nucleopolyhedrovirus, and two fungi: Paecilomyces spp. and Hirsutella gigantean. At Beartown State Forest in Monterey, MA, adult moths were observed predated upon by birds. The birds fed upon the moths, leaving behind only their wings as evidence of their feeding.
Abamectin (NL)
Acephate (NL)
Acetamiprid (L)
Azadirachtin (NL)
Beauveria bassiana (NL)
Bifenthrin (NL)
Bifenthrin+imidacloprid (L)
Chlorantraniliprole (NL)
Chlorpyrifos (larvae) (N)
Cyantraniliprole (NL)
Cyfluthrin (NL)
Flonicamid+cyclaniliprole (N)
Tau-fluvalinate (NL)
Gamma-cyhalothrin (L)
Horticultural oil (L)
Indoxacarb (L)
Insecticidal soap (NL)
Isaria (paecilomyces) fumosoroseus (NL)
Lambda-cyhalothrin (L)
Malathion (L)
Neem oil (NL)
Pyrethrin+sulfur (NL)
Spinetoram+sulfoxaflor (N)
Spinosad (NL)
Tebufenozide (NL)
Active ingredients that may be applied systemically include: Abamectin (injection), acephate (injection), acetamiprid (injection), azadirachtin (injection, soil drench), chlorantraniliprole (soil drench), cyantraniliprole (soil drench, soil injection), and neem oil (soil drench).
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.
