Alsophila

Females are immediately recognizable by their complete lack of wings—appearing as small, gray-brown, caterpillar-like moths that crawl up tree trunks. Males are small, gray-brown moths with functional wings and typical moth appearance; they are active fliers attracted to light. Larvae are slender, with only two or three pairs of prolegs at the rear, producing the characteristic looping "inching" locomotion. Color morphs include light green and dark brown.

Larvae feed on hardwood trees including oaks, maples, elms, birch, and lindens. Adults emerge from soil pupation sites and females climb vertical structures (trees, buildings) to oviposit. Found in deciduous forests, urban shade tree plantings, and suburban landscapes across eastern North America.

Eastern North America, with records from Maryland, Virginia, North Carolina, Massachusetts, and adjacent regions. Range extends broadly across the continent where suitable host trees occur.

Adults emerge from soil in late autumn (fall cankerworm, A. pometaria) or early spring (spring cankerworm, A. pometaria—note: specific species seasonality varies), with females releasing pheromones on mild winter nights. Eggs hatch in early spring, synchronized with leaf bud break. Larvae feed through spring and early summer, then pupate in soil.

Larvae feed on leaves of hardwood trees, particularly oaks, maples, elms, and lindens. Young larvae create "shot hole" damage in tender young leaves; mature larvae consume entire leaves leaving only midribs and major veins.

Eggs laid on bark of twigs and branches in late autumn or winter. Larvae hatch in early spring, feed for several weeks, then descend to ground on silk threads to pupate in soil. Adults emerge from pupae after several months of diapause. Females die shortly after oviposition; they do not feed as adults.

Larvae exhibit characteristic "inching" locomotion: arching body into loop by alternating grasp between anterior and posterior legs. When disturbed, larvae drop from foliage on silk threads. Females release sex pheromones shortly after sunset on mild winter nights to attract flying males. Males track pheromone plumes to locate females.

Native defoliator of deciduous forests. Periodic outbreaks can cause extensive tree defoliation, though healthy trees typically recover. Serves as food source for birds, spiders, rodents, and predatory insects. Population dynamics regulated by natural enemies, food quality, and weather.

Significant pest of urban and suburban shade trees during outbreak years. Repeated defoliation can weaken stressed trees, increasing susceptibility to secondary pests and diseases. Management options include Bacillus thuringiensis (Bt), spinosad, and other insecticides; barrier bands on tree trunks have shown limited effectiveness. Notable outbreak years include 2015 in Maryland and surrounding states.

• Paleacrita vernata (spring cankerworm)Similar wingless females and inchworm larvae; distinguished by spring adult emergence and slightly different larval morphology. Often co-occurs with Alsophila species.
• Operophtera brumata (winter moth)Close relative with flightless females; invasive in New England, causing similar defoliation. Distinguished by geographic range and specific host preferences.
• Lambdina fiscellaria (linden looper)Member of same clan with flightless females and similar life history; associated with linden and other hardwoods.

• sexual dimorphism
• wingless female
• inchworm
• defoliator
• outbreak pest
• geometrid
• native pest
• urban forestry

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Chilly winter days can’t stop the fall cankerworm, Alsophila pometaria — Bug of the Week
• Wintry appearance of a strange moth: Fall cankerworm, Alsophila pometaria — Bug of the Week
• Inch by inch: Fall cankerworm, Alsophila pometaria — Bug of the Week
• Cankerworm conundrums: Fall cankerworm, Alsophila pometaria — Bug of the Week
• A moth in winter - the fall cankerworm, Alsophila pometaria — Bug of the Week
• Inch by Inch, Fall Cankerworms Will Eat Your Trees
• Predicting the Potential Suitable Distribution of Alsophila spinulosa under Climate Change Scenario
• Soil microbial community composition and diversity in the rhizosphere of Alsophila spinulosa growing in different habitats within the Chishui Alsophila National Nature Reserve in Guizhou Province, China