Estigmene acrea

Drury, 1773

Salt Marsh Moth, Acrea Moth

Estigmene acrea, commonly known as the salt marsh or acrea moth, is a native North American moth in the Erebidae. The is notable for its highly variable caterpillar coloration, ranging from pale yellow to dark brown or black, and its unique relationship with —compounds it can detoxify and convert into . display striking : males have yellow-orange hindwings while females have white hindwings, with both sexes bearing black spots. The species exhibits unusual mating including male formation and female calling.

Estigmene acrea by (c) Jake McCumber, some rights reserved (CC BY), uploaded by Jake McCumber. Used under a CC-BY license.

Estigmene acrea by (c) Jon Sullivan, some rights reserved (CC BY). Used under a CC-BY license.

Estigmene acrea by (c) Justin Williams, some rights reserved (CC BY), uploaded by Justin Williams. Used under a CC-BY license.

Pronunciation

How to pronounce Estigmene acrea: /ɛˈstɪɡmɪni ˈækrɪə/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

distinguished from similar white tiger moths by combination of white forewings with black spotting, yellow-orange (male) or white (female) hindwings with black spots, and yellow-orange with black spots. Caterpillars recognized by dense hair in tufts, variable coloration, segmental white dots, and rows of orange or black warts. Resembles banded woolly bear (Pyrrharctia isabella) but lacks black terminal bands; resembles giant woolly bear (Hypercompe scribonia) but is smaller and less uniformly black.

Images

Habitat

Occurs in diverse including salt marshes, meadows, fields, agricultural areas, and disturbed sites. attracted to flowers and honeydew. Larvae feed on broad range of herbaceous and woody plants.

Distribution

Native to North America from southern Canada (Ontario, Quebec, Alberta, Manitoba, Saskatchewan) throughout the United States, extending south through Mexico to Colombia. Also recorded from Democratic Republic of Congo and Kenya. Most abundant as a pest in the southwestern United States.

Seasonality

generally active May to August in northern portions of range; year-round in southern Florida and southern Texas. Multiple per year in southern range; single generation with larvae in northern range.

Diet

Caterpillars are , feeding on dandelion, cabbage, cotton, walnut, apple, tobacco, pea, potato, clover, maize, and numerous other herbaceous and woody plants. feed on nectar and honeydew.

Host Associations

dandelion - larval food plant
cabbage - larval food plant
cotton - larval food plant
walnut - larval food plant
apple - larval food plant
tobacco - larval food plant
pea - larval food plant
potato - larval food plant
clover - larval food plant
maize - larval food plant

Life Cycle

laid in clusters on plant leaves. Larvae hatch and feed through growing season; in northern range, partially grown larvae overwinter and resume feeding in spring before pupating. In southern range, multiple occur with continuous development. Larvae pupate in hair-and-leaf cocoons. emerge and mate; females call to males from within .

Behavior

Exhibits unique dual mating system: males form (aggregated display sites) where they inflate abdominal coremata and release derived from ingested ; females also actively call to males using (Z,Z)-3,6-cis-9,10-epoxyheneicosadiene. Calling peaks during second through fourth nights after , with bimodal calling pattern. Mated females produce significantly less pheromone than virgins. attracted to ultraviolet light.

Ecological Role

Caterpillars serve as herbivores and prey for including ichneumon Therion morio. may function as when nectaring. Unique alkaloid metabolism allows utilization of plants containing that are toxic to most other herbivores, potentially reducing competition for these resources.

Human Relevance

Occasional agricultural pest, particularly in southwestern United States, damaging corn, cotton, and other crops. Caterpillars known as "salt marsh caterpillars" or "woollybears"; sometimes confused with weather-predicting banded woolly bears (Pyrrharctia isabella) in folklore. Used in scientific research on insect-plant chemical interactions, , and lekking .

Similar Taxa

Pyrrharctia isabella (Isabella Tiger Moth)Banded woolly bear caterpillar has distinct black-orange-black banding pattern; E. acrea lacks black terminal bands and has more variable coloration
Hypercompe scribonia (Giant Leopard Moth)Giant woolly bear caterpillar is larger, uniformly black with crimson intersegmental rings when disturbed, and has more formidable spine defense; E. acrea smaller with variable coloration
Spilosoma virginica (Virginia Tiger Moth)Yellow bear caterpillar more uniformly pale yellow; E. acrea more variable with distinct segmental markings

Misconceptions

Despite "salt marsh caterpillar" and superficial resemblance to banded woolly bear, this has no demonstrated ability to predict winter weather—a folklore attribute properly associated with Pyrrharctia isabella.

More Details

Alkaloid Metabolism

Unique among insects in ability to detoxify from plants and convert them into male courtship . This involves hydrolysis to retronecine and re-esterification to insect-specific alkaloids. The alkaloids also stimulate growth of male coremata (pheromone-disseminating organs).

Sexual Dimorphism

Hindwing coloration differs between sexes: males have yellow-orange hindwings, females have white hindwings. This is unusual among tiger moths and may play role in mate recognition.

Pest Status

Documented as pest of corn in Mexico and known to damage crops in Ontario and Quebec, Canada. Most significant economic impact in southwestern United States.