The maple trumpet skeletonizer is a moth as an adult, and found throughout much of New England and parts of Canada. Adult moths are gray, 15 mm in length, and are present as early as April in the spring, and attracted to lights at night. Adult females will lay their eggs randomly on the undersides of host plant leaves in late June through mid July. Eggs hatch, and the larvae feed on the tissue between the larger leaf veins on the underside of the leaf, leaving a very thin layer of the upper leaf epidermis behind. Caterpillars are active from early-July to early-October. The caterpillar then spins silken webs on the underside of the leaf, folds it, and inside the fold creates a trumpet-shaped tube of silk and frass. Tubes may be approximately 5 cm in length. Caterpillars feed using the tube for protection and skeletonize the leaf beneath the webbing. Maple trumpet skeletonizer caterpillars are pale yellow-green with yellowish heads. At maturity, they can be up to 13 mm long. Once mature, the caterpillars drop to the ground and create a cocoon between two fallen leaves.
The undersides of sugar maple leaves are impacted by this insect, however it can feed on other hosts especially when maple is scarce. (May be confused for a similar species found on oak.) Larvae skeletonize and fold leaves and create webbing. The maple trumpet skeletonizer rarely requires management, however, even when populations are heavy because it causes this damage late in the growing season. Minor damage from this insect is common every year, however occasionally outbreaks will occur. Activity from this insect is rarely damaging to plant health.
Look for adult moths attracted to lights at night in April in the spring. Flip leaves over to look for caterpillars and the damage they cause from early-July to early-October. In particular, flip over any skeletonized leaves with only a thin layer of epidermis remaining on a section of the upper side of the leaf. Folded leaves can be pulled apart to look for the trumpet-shaped tubes of silk and frass found within.
Infestations of maple trumpet skeletonizers can be reduced by raking and destroying or removing dropped leaves nearby impacted host trees in the fall.
Populations of this native insect are often kept below damaging levels due to reported parasitoid activity, thus requiring no chemical management. The identity of the parasitoids or further information about other natural enemies such as predators or pathogens is currently unavailable.
Abamectin (NL)
Acephate (larvae) (NL)
Bifenthrin (NL)
Chlorantraniliprole (larvae) (NL)
Cyantraniliprole (larvae) (NL)
Cyfluthrin (larvae) (NL)
Flonicamid+cyclaniliprole (L)
Gamma-cyhalothrin (L)
Horticultural oil (L)
Indoxacarb (larvae) (L)
Lambda-cyhalothrin (larvae) (L)
Malathion (larvae) (L)
Neem oil (larvae) (NL)
Pyrethrin+sulfur (larvae) (NL)
Spinetoram+sulfoxaflor (larvae) (NL)
Spinosad (larvae) (NL)
Tebufenozide (larvae) (NL)
Chemical management of this insect is typically not necessary, and a best practice would be to tolerate its presence in ornamental landscapes. Active ingredients listed above are found in products labeled for use against “caterpillars” and “Lepidopterous insects”.
Active ingredients that may be applied systemically include: abamectin (injection), acephate (injection), 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.