Macaria aemulataria

The angular forewing margin distinguishes this species from most other Macaria. The pale gray-brown coloration with fine lines and small discal spot separates it from darker or more boldly patterned congeners such as M. bisignata (the red-headed inchworm moth), which has more contrasting markings and often reddish tones. Similar species with angular wings include M. pustularia, which has more prominent spotting and different wing shape.

Wingspan 20–22 mm. Forewings have a distinct angular or notched outer margin, giving the species its common name. Ground color is pale gray to brownish with fine, darker transverse lines. A small dark discal spot is usually present. Hindwings are paler with less pronounced patterning. Body is slender and relatively small for the family.

Deciduous forests and woodlands, particularly areas with maple (Acer) host plants. Found in both mature forests and suburban or park settings where maples are present. Elevation range spans sea level to at least moderate montane elevations in the western part of its range.

Eastern and central North America: Nova Scotia south to Florida, west to Texas, north to Alberta, Oregon, and the Prairie Provinces. Records confirmed from Alberta, Manitoba, Saskatchewan (Canada) and Vermont (USA) among other provinces and states.

Adults active mid-June to mid-July in Alberta; May to September in Ohio. Flight period extends across summer months, with peak activity varying by latitude—earlier and more extended in the south, shorter and later in the north.

Larvae feed on Acer species (maples). Specific Acer species documented as hosts include sugar maple and likely other native and ornamental maple species.

• Acer - larval host plantmaple species

Complete metamorphosis with egg, larval, pupal, and adult stages. Larvae are inchworms (typical of Geometridae) with reduced prolegs. Overwintering stage not explicitly documented in sources but likely as pupa given family patterns. Single or multiple generations per year depending on latitude; Ohio records suggest extended flight period possibly indicating partial second generation or extended emergence.

Adults are nocturnal and attracted to light. Larvae are foliage feeders on maple leaves, moving with characteristic looping gait of geometrid caterpillars.

Larval herbivore on maple foliage; contributes to nutrient cycling in deciduous forest ecosystems. Serves as prey for birds, parasitoid wasps, and other insectivores. Not considered a significant pest despite feeding on economically important host trees.

Occasional presence in urban and suburban areas due to widespread planting of ornamental maples. No significant economic impact; not a forestry pest. Sometimes encountered at porch lights and in moth surveys.

• Macaria bisignataRed-headed inchworm moth has more contrasting dark markings and often reddish tones; lacks the pale, uniform gray-brown appearance of M. aemulataria.
• Macaria pustulariaHas more prominent spotting and different wing shape despite also having somewhat angular forewings.
• Other Macaria speciesMost lack the distinctly angular forewing margin that characterizes M. aemulataria; many have straighter or more rounded wing edges.

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life