Moths of North Carolina
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250 NC Records

Euclea delphinii (Boisduval, 1832) - Spiny Oak-slug Moth



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Taxonomy
Superfamily: Zygaenoidea Family: LimacodidaeP3 Number: 660051.00 MONA Number: 4697.00
Comments: Euclea delphinii is one of five species of Euclea that are found in North America, and the only one that is currently known from North Carolina.
Species Status: Barcoding indicates that Florida populations of E. delphinii are well separated from Euclea nanina, but it is unclear whether these two are distinct elsewhere, including North Carolina (Marc Epstein, pers. comm. to J.B. Sullivan, 2015). More work is needed to determine whether there are any diagnostic characters that can be used to separate these species outside of Florida.
Identification
Field Guide Descriptions: Covell (1984); Beadle and Leckie (2012)Online Photographs: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Forbes (1923)Technical Description, Immature Stages: Wagner (2005); Marquis et al. (2019)                                                                                  
Adult Markings: In this species the palps, antennae, head, thorax and legs are all brown. The forewing ground color is similar, but with a tendency to be more reddish brown or faintly purplish brown. The forewing often has a violet sheen and typically bears a black discal spot. The forewing has a well-defined, elongated orange patch in the upper half of the median area and a smaller, less well-defined, orange patch or orange spot in the sub-terminal area near the apex that is sometimes reduced or absent. The most conspicuous marks are two white-edged, pistachio green patches. The largest is in the basal area below the inner margin, and is immediately anterior and adjacent to the larger orange patch. The second is smaller and is in the postmedian area near the costa. It is immediately anterior and adjacent to the smaller orange patch (if present). The shape and distribution of green coloration can range from small discrete patches to connected patches that encompass much of the forewing (the "green form" is regularly encountered in the Midwest but is rare to very rare in the East).

Differentiation of E. delphinii from the very similar E. nanina can be a challenge. According to Neumoegen and Dyar (1894), the spots in delphinii are more angular, with the discal spot more extended than in E. nanina. In the latter the spots are more rounded and the discal spot in particular is more punctiform. According to J.D. Roberts (pers. comm. to P. Backstrom), the green basal patch is proportionally smaller than that of E. nanina and either borders or stops very close to vein CuA, not drifting over the vein. In nanina the green basal patch always rises just above vein CuA. Size is also indicative with E. delphinii always being the significantly larger of the two. Until these field marks are correlated with significant differences found in DNA or structural features, none of these differences can be considered definitive. In the meantime, we lean more towards the characters originally used by Neumoegen and Dyar (1894) and Dyar (1899). Length of the forewing should be recorded where possible, particularly if E. nanina is suspected.
Wingspan: 25-30 mm (Forbes, 1923)
Adult Structural Features: The male antenna is closely pectinate at the base but serrate in the outer third (Forbes, 1923).
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: Dyar (1897c) reported on the life history of this species in New York where populations are single-brooded. The females emerge at night in late June or July and mostly lay their eggs singly on leaves, but occasionally in small clusters (also see Murphy et al. 2011). The eggs hatch in about a week and the larvae pass through eight or nine instars, with mature larvae present in September. The last instars spin cocoons and overwinter on the ground, with pupation occurring in the spring.

The larvae of this species are exceptionally variable in color. The ground color of mature larva can be a shade of green, yellow, pink, orange-brown, steel blue, or gray (Marquis et al, 2019). The dorsal area is slightly depressed and usually has a white to pale green mid-dorsal longitudinal line, a pair of white dots on each segment, and a pair of thin, black, sinuate longitudinal stripes around the spots. The subdorsal area is cream to orange, with a variable amount of red to brown patches that sometimes form a line, and a row of pointed green, orange, or yellow spine clusters on each segment (Marquis et al, 2019). Those on the anterior and posterior abdominal segments tend to be white or black tipped and longer than the others. The sides of the body have white specks and black markings that vary from a line to almost a series of circles, with elongated spine clusters present on each segment. Wagner (2005) noted that the last two instars are best recognized by their overall shape and the presence of two or four patches of black detachable spines at the rear of the body. Despite the numerous spines, the sting of the larvae is said to be relatively mild.
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Euclea delphinii is broadly distributed across most of the eastern US and in adjoining areas of southern Canada (Ontario; Quebec; New Brunswick). In the US the range extends from Maine southward to southern Florida, and westward to eastern Texas, Oklahoma, eastern Kansas, eastern North Dakota, Iowa and Minnesota. This species occurs statewide from the barrier islands in the east to higher elevations in the Blue Ridge.
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: The adults have been observed year-round in Florida and mostly from April through October elsewhere. As of 2023, our records extend from mid-April through late November. The adults fly primarily from May to August in the Piedmont and Blue Ridge, but have a more prolonged flight in the Coastal Plain.
Habitats and Life History
Habitats: Local populations are generally found in or near deciduous hardwoods. We have records from essentially all hardwood or mixed pine-hardwood habitats that occur across the state, including hydric, mesic, and xeric habitats. This species can also be found in semi-wooded residential neighborhoods, along fencerows, and in other habitats where hardwood trees are present.
Larval Host Plants: The larvae are highly polyphagous and feed on a large number of hardwood trees and shrubs, with oaks (Quercus) being the most important host taxa in many areas (Dyar, 1897b; Wagner, 2005; Heppner, 2007; Robinson et al., 2010; Murphy et al., 2011; Marquis et al., 2019). The reported host include Sugar Maple (Acer saccharum) and other maples, alders (Alnus), serviceberries (Amelanchier), Andromeda, birches (Betula), American Hornbeam (Carpinus caroliniana), Eastern Redbud (Cercis canadensis), Bitternut Hickory (Carya cordiformis), Pignut Hickory (C. glabra), American Chestnut (Castanea dentata), hackberries (Celtis), cocoplums (Chrysobalanus), Citrus species, Seagrapes (Coccoloba uvifera), hawthorns (Crataegus), American Persimmon (Diospyros virginiana), American Beech (Fagus grandifolia), figs (Ficus), ashes (Fraxinus), Honey Locust (Gleditsia triacanthos), Hibiscus, Dahoon Holly (Ilex cassine), Yaupon Holly (I. vomitoria), magnolias (Magnolia), commercial apples (Malus domestica), Common Waxmyrtle (Morella cerifera), Black Gum (Nyssa sylvatica), American Sycamore (Platanus occidentalis), poplars (Populus), Carolina Laurel Cherry (Prunus caroliniana), Black Cherry (P. serotina), Common Pear (Pyrus communis), White Oak (Quercus alba), Bear Oak (Q. ilicifolia), Shingle Oak (Q. imbricaria), Laurel Oak (Q. laurifolia), Northern Red Oak (Q. rubra), Black Oak (Q. velutina), Live Oak (Q. virginiana), Red Mangrove (Rhizophora mangle), rhododendrons (Rhododendron), brambles (Rubus), Weeping Willow (Salix babylonica) and other willows, greenbriars (Smilax), American Basswood (Tilia americana), elms (Ulnus) and blueberries (Vaccinium). - View
Observation Methods: The adults are readily attracted to lights, but like other limacodids do not come to bait or visit flowers. The larvae are frequently seen in the late summer and early autumn, particularly when they leave their host plants and wander in search of pupation sites.
Wikipedia
See also Habitat Account for General Forests and Shrublands
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: This species is common across the state and utilizes a very broad range of habitats and host plants. it appear to be quite secure in North Carolina.

 Photo Gallery for Euclea delphinii - Spiny Oak-slug Moth

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

Recorded by: Mark Basinger on 2024-07-11
Brunswick Co.
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Recorded by: Mark Basinger on 2024-07-11
Brunswick Co.
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Recorded by: R. Newman on 2024-07-07
Carteret 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: K. Bischof on 2024-06-24
Transylvania 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: Owen McConnell and Simpson Eason on 2024-06-21
Graham Co.
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Recorded by: Jim Petranka on 2024-06-13
Madison Co.
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Recorded by: Emily Stanley on 2024-06-06
Buncombe Co.
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Recorded by: Jim Petranka on 2024-05-27
Madison Co.
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Recorded by: Owen McConnell on 2024-05-25
Graham Co.
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Recorded by: K. Bischof on 2024-05-24
Transylvania Co.
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Recorded by: Mark Basinger on 2024-05-22
Wilson Co.
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Recorded by: Mark Basinger on 2024-05-22
Wilson Co.
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Recorded by: Mark Basinger on 2024-04-28
Brunswick Co.
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Recorded by: Mark Basinger on 2024-04-28
Brunswick Co.
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Recorded by: Erich Hofmann and Kayla Weinfurther on 2024-04-28
New Hanover Co.
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Recorded by: Erich Hofmann and Kayla Weinfurther on 2024-04-28
New Hanover Co.
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Recorded by: R. Newman on 2023-09-06
Carteret Co.
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Recorded by: David George on 2023-08-20
Orange Co.
Comment: feeding on Carya sp.
Recorded by: R. Newman on 2023-08-19
Carteret Co.
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Recorded by: Jim Petranka on 2023-08-15
Madison Co.
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Recorded by: Stephen Dunn on 2023-08-14
Orange Co.
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Recorded by: Rosanna Bonilla, Amber Williams, Michael P. Morales on 2023-08-11
Cumberland Co.
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Recorded by: Rosanna Bonilla, Amber Williams, Michael P. Morales on 2023-08-11
Cumberland Co.
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Recorded by: David George, Stephen Dunn, Jeff Niznik on 2023-07-31
Macon Co.
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Recorded by: David George, Stephen Dunn, Jeff Niznik on 2023-07-31
Swain 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: Emily Stanley on 2023-07-08
Yancey Co.
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Recorded by: Jim Petranka on 2023-07-07
Madison Co.
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