Moths of North Carolina
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149 NC Records

Acharia stimulea (Clemens, 1860) - Saddleback Caterpillar Moth


Taxonomy
Superfamily: Zygaenoidea Family: LimacodidaeP3 Number: 660055.00 MONA Number: 4700.00
Comments: This is one of two representatives of this genus that occur in North America and the only one that is found in North Carolina. This species was placed in the genus Sibine in older references.
Identification
Field Guide Descriptions: Covell (1984; as Sibine stimulea); Beadle and Leckie (2012)Online Photographs: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Forbes (1923)Technical Description, Immature Stages: Wagner (2005)                                                                                 
Adult Markings: Acharia stimulea is the largest of our slug moths, with the length from the tip of head to the apex of the forewing at rest averaging 18.5 mm (n = 5) for North Carolina specimens. The body is stout and dark brown, with heavy, brown, furry legs and broad, dark reddish-brown to dark brown forewings. The only conspicuous marks on the forewing are white dots, with one (occasionally two) centered near the base of the forewing and two (rarely one or three) in the subcostal region at around three-fourths the distance from the wing base to the apex. There are also broad longitudinal swaths of silvery-blue scales that are largely concentrated through the middle of the wing, along the costa, and along the inner margin. These impart a shiny appearance when stuck by light at certain angles. When combined with brown or reddish-brown areas that lack the silvery-blue scales, it gives the forewing a distinctive appearance.
Wingspan: 2.6 - 4.3 cm, with females larger than the males (Covell, 1984).
Adult Structural Features: The male antenna is pectinate at the base and simple in the outer half, while the hind tibia has only a single pair of spurs (Forbes, 1923).
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: The larvae are highly polyphagous and feed on a very wide variety of plants. The females lay masses of 30-50 eggs on the upper sides of the leaves of the host plant, and the hatchlings typically emerge around 10 days later (Dyar and Morton, 1896). The early instars commonly feed communally on both sides of the leaves and skeletonize them by scraping off patches of tissue with their mandibles. Around the third or fourth instar, they transition to group edge-feeding and consume the entire leaf tissue except for the tougher veins. The oldest instars consume the entire leaf, including the veins (Bibbs and Frank, 2012). Group feeding may help to ward off predators and increase growth by rapidly consuming the leaves before the host plants can synthesize defensive allelochemicals (Fiorentino, 2014). The larval stage last 4-5 months and has eight instars. The final-instar larvae spin tough, fibrous cocoons and incorporate stinging spines and calcium oxalate into them (Bibbs and Frank, 2012; Fiorentino, 2014). Overwintering occurs in the pupal stage on the ground.

The larva is among the most distinctive of all caterpillars. It has a lime green saddle with a brown center. Both the outer margin of the saddle and the brown center are edged with white. There are several pairs of lobes on the thorax and a matching set of large lobes on the posterior end that bear long, stinging spines with venom that pack a formidable sting when contacted by skin. The sting is described by Wagner (2005) as being among the most potent of any North American slug caterpillar, a claim that can be attested to by many gardeners. The sting is typically accompanied by local redness and swelling, and even blistering if the spines are not quickly removed (Diaz, 2005).
Larvae ID Requirements: Unmistakable and widely known.
Distribution in North Carolina
Distribution: Acharia stimulea occurs throughout much of the eastern US and adjoining areas on southern Ontario, as well as in Central America and northwestern South America. In the US the range extends from Massachusetts and Connecticut southward to southern Florida, and westward to eastern Texas, Arkansas, eastern Oklahoma, Missouri, northeastern Kansas, southeastern Nebraska, Illinois, and southeastern Iowa. This species occurs statewide in North Carolina, from the barrier islands to higher elevations in the Blue Ridge, but is relatively uncommon in the Coastal Plain where hardwoods are less prevalent.
County Map: Clicking on a county returns the records for the species in that county.
Flight Dates:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

Click on graph to enlarge
Immature Dates:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

Click on graph to enlarge
Flight Comments: Populations in southern Florida are active year-round and appear to produce two generations per year, while those farther north are univoltine, with the adults typically flying from May through September. Local populations in North Carolina are also univoltine. As of 2023, our records extend from late-May through mid-October, with a seasonal peak in June and July.
Habitats and Life History
Habitats: We have records from a wide variety of habitats, including maritime forests and scrub, sandhills, peatlands, lake and pond shorelines, and both mesic forests and drier ridge tops. This species is also commonly found in residential areas, in gardens, and in corn fields.
Larval Host Plants: The larvae are highly polyphagous (Baker, 1972; Wagner, 2005; Heppner, 2007; Robinson et al., 2010; Bibbs and Frank, 2012; Murphy et al., 2011; Marquis et al., 2019). Bibbs and Frank (2012) provide a comprehensive lists that includes members of 41 plant families, including many with tropical or subtropical affinities. We are not including a comprehensive list here, but do list native species that are used in temperate communities and are relevant to North Carolina. These include Boxelder (Acer negundo), Silver Maple (A. saccharinum), Common Pawpaw (Asimina triloba), Pignut Hickory (Carya glabra), Pecan (C. illinoinensis), Shagbark Hickory (C. ovata), chestnuts (Castanea), hackberries (Celtis), Buttonbush (Cephalanthus occidentalis), Flowering Dogwood (Cornus florida) and other dogwoods, American Beech (Fagus grandifolia), Northern Spicebush (Lindera benzoin), Black Cherry (Prunus serotina), White Oak (Quercus alba), Scarlet Oak (Q. coccinea), Bur Oak (Q. macrocarpa), Pin Oak (Q. palustris), Chestnut Oak (Q. montana), Northern Red Oak (Q. rubra), Black Oak (Q. velutina), Black Locust (Robinia pseudoacacia), willows (Salix), Sassafras (Sassafras albidum), American Basswood (Tilia americana), Poison-oak (Toxicodendron pubescens), elms (Ulmus), blueberries (Vaccinium) and grapes (Vitis). Many non-native ornamentals and corn are also commonly used. As of 2023, we have observed the species feeding on spicebush, hickory, buttonbush, beech, apple, cherry, grape, and greenbrier, as well as a variety of garden plants. - View
Observation Methods: The adults are attracted to lights, but like other limadodids do not appear to come to bait or to visit flowers. Many of our records are for the boldly marked larvae that often feed in the open in communal groups, and are well-recognized by the general public.
Wikipedia
See also Habitat Account for General Forests and Fields
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: G5 [S5]
State Protection: Has no legal protection, although permits are required to collect it in state parks and on other public lands.
Comments: Acharia stimulea is common across the state and uses a wide range of habitats and host plants. It appears to be quite secure within the state.

 Photo Gallery for Acharia stimulea - Saddleback Caterpillar Moth

77 photos are available. Only the most recent 30 are shown.

Recorded by: David George on 2024-07-20
Chatham Co.
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Recorded by: Stephen Dunn on 2024-07-19
Orange Co.
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Recorded by: David George, Jeff Niznik, Stephen Dunn on 2024-06-29
Chatham Co.
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Recorded by: Emily Stanley on 2024-06-26
Buncombe Co.
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Recorded by: Mark Basinger on 2024-06-23
Yancey Co.
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Recorded by: Mark Basinger on 2024-06-23
Yancey Co.
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Recorded by: David George, Stephen Dunn, Jeff Niznik, Patrick Coin on 2024-06-22
Chatham Co.
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Recorded by: Andrew W. Jones on 2023-10-02
Polk Co.
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Recorded by: K. Bischof on 2023-09-18
Transylvania Co.
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Recorded by: David George, Stephen Dunn, Jeff Niznik on 2023-09-15
Orange Co.
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Recorded by: David George, Stephen Dunn, Jeff Niznik on 2023-09-07
Chatham Co.
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Recorded by: John Petranka on 2023-09-07
Orange Co.
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Recorded by: David George, Jeff Niznik on 2023-09-04
Orange Co.
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Recorded by: David George on 2023-08-20
Orange Co.
Comment: Larva was feeding on Northern Spicebush
Recorded by: David George, Jeff Niznik on 2023-08-14
Orange Co.
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Recorded by: Erich Hofmann on 2023-08-08
New Hanover Co.
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Recorded by: Erich Hofmann on 2023-08-08
New Hanover Co.
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Recorded by: David George, Stephen Dunn, Jeff Niznik, Rich Teper, Becky Watkins on 2023-07-30
Swain Co.
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Recorded by: Dean Furbish on 2023-07-22
Wake Co.
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Recorded by: Jim Petranka on 2023-07-14
Madison Co.
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Recorded by: Jim Petranka on 2023-07-07
Madison Co.
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Recorded by: Jim Petranka and Chuck Smith on 2023-06-29
Madison Co.
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Recorded by: David George, Stephen Dunn on 2022-09-09
Orange Co.
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Recorded by: Morgan Freese on 2022-08-19
Buncombe Co.
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Recorded by: Gary Maness on 2022-07-15
Guilford Co.
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Recorded by: Jim Petranka on 2022-07-14
Madison Co.
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Recorded by: Vin Stanton on 2022-07-10
Buncombe Co.
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Recorded by: tom ward on 2022-07-09
Buncombe Co.
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Recorded by: Gary Maness on 2022-07-02
Guilford Co.
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Recorded by: David George on 2022-06-26
Durham Co.
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