Moths of North Carolina
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34 NC Records

Synanthedon rileyana (Edwards, 1881) - Riley's Clearwing

Synanthedon rileyanaSynanthedon rileyanaSynanthedon rileyanaSynanthedon rileyana
Taxonomy
Superfamily:
Sesioidea		 Family:
Sesiidae		Subfamily:
Sesiinae		Tribe:
Synanthedonini		P3 Number:
55a0093		 MONA Number:
2552.00
Comments: North America has 136 or more species in the family Sesiidae, and the large genus Synanthedon constitutes around half of the 37 species found in North Carolina, many being similar in appearance to one another. Some sesiids, known broadly as clearwing borers, are significant pests of commercial crops. Almost all are mimics of wasps and hornets.
Identification
Field Guide Descriptions: Covell (1984); Beadle and Leckie (2018)Online Resources: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Eichlin and Duckworth (1988)Technical Description, Immature Stages: Engelhardt (1946)                                                                                 
Adult Markings: Synanthedon rileyana appears to be a Batesian mimic of the Eastern Yellowjacket (Vespula maculifrons), with a black abdomen that is boldly marked with yellow crossbands. The antenna is black above and the discal mark on the forewing is bright red. The following detailed description of the male is based on those of Engelhardt (1946) and Eichlin and Duckworth (1988).

The antenna is robust and black above, with strong, even pectinations. The labial palp has a rough brush and is bright yellow with black on the sides. The head is black above, with a pale-yellow face and a yellow collar. The thorax is black with long yellow tufts posteriorly, and with the posterior margin edged with golden yellow. A yellow mark is present at the base of forewing and there is a yellow patch beneath at the sides. The forewing is mostly hyaline with an oblong, distinctly red discal mark, along with narrow brownish margins that are variously powdered with orangish-red, particularly on the basal margins. The legs are rough and largely yellow to yellow-orange with some blackish shading. The hindwing is also hyaline, with very narrow margins and a small orange-red discal spot. The abdomen is cylindrical in shape, black, and ringed with yellow on the posterior edge of segments 2-7. The anal tuft is short, with a mixture of yellow and black longitudinal bands, and with lateral tufts that are short and flared.

The females are very similar to the males, but differ in being longer on average, in having the costa and margins of the forewing that are broader, and in having an anal tuft that is narrower, black, and only slightly intermixed with yellow.
Wingspan: 18-24 mm for males and 20-30 mm for females (Engelhardt, 1946).
Forewing Length: 7-12 mm (Eichlin and Duckworth, 1988).
Adult Structural Features: (see below)
Structural photos
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: The larvae are root borers that feed on Carolina Horsenettle (Solanum carolinense) and perhaps other members of the Solanaceae. The following life history account is based on observations reported by Engelhardt (1946) in New York and Wise (2007) in Virginia. After emerging and mating, the females either drop their rounded, brownish eggs directly on the ground near the host plant, or deposit them in small clusters of three or more on the leaves and stems of the host plant. The hatchlings burrow through the soil where they presumably bore into the roots from the outside and feed near the cortex. Feeding is largely confined to the taproots and thick, lateral roots. The main roots commonly contain larvae in various stages of growth during August and in the spring, which indicates that this species overwinters as larvae. Prior to pupating, the larvae exit the roots and construct flimsy silk-lined tubes that extend from near the ground surface to 8-25 cm deep in the soil. Pupation occurs in the tubes, and Engelhardt (1946) noted that the living pupae will quickly descend to the very bottom when disturbed. At emergence, the pupa pushed through the soil surface and the adult emerges shortly thereafter. The pupal skins are commonly left at the soil surface below the host plant, which is a good way to locate infected plants. Local populations are univoltine and require about one year to complete the life cycle.

Both Engelhardt (1946) and Wise (2007) reported that the stems are not used, and that boring is restricted to the roots. These observations conflict with those of Somes (1916), who studied this species in Missouri and reported that the larvae bore in both the stems and roots of Carolina Horsenettle. Larvae that were around the third-instar were found in the stems in late-May. Since the plant dies back with the arrival of cold weather, this implies that overwintering larvae in the roots moved upwards into the stem after the spring warm-up. Somes (1916) transferred larvae to tomato and potato stems and the larvae readily bored in these. It is possible that he confused Synanthedon rileyana larvae with one of the stem-boring species that feed on tomatoes and potatoes. Additional clarification is needed to determine whether S. rileyana actually bores in stems.
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Synanthedon rileyana is broadly distributed in the eastern US , except in the southeastern Coastal Plain where it is absent or rare in most areas. The range extends from New Hampshire, Vermont and New York southward to northern Georgia and southern Alabama, and westward to eastern Texas, Oklahoma, eastern Kansas, Missouri and Iowa. As of 2024, we have records from all three physiographic regions of the state, but with no records for the central and southern portions of the Coastal Plain.
County Map: Clicking on a county returns the records for the species in that county.
Synanthedon rileyana
Flight 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 from June through November in different regions of the US, with a seasonal peak in activity typically during July and August. As of 2024, our records extend from mid-June through early-October, with populations being univoltine.
Habitats and Life History
Habitats: Local populations are generally found in open, disturbed habitats such as waste areas, roadsides, fields, and sand prairies where the host plant grows.
Larval Host Plants: This is the only clearwing moth in North America that feeds on members of the Solanaceae. The only known host as of 2024 is Carolina Horsenettle (Solanum carolinense) (Somes, 1916; Engelhardt, 1946; Eichlin and Duckworth, 1988; Taft et al., 2004; Wise, 2007). - View
Observation Methods: The adults are diurnally active and are often seen perched on vegetation during the day. They are not attracted to lights or bait, but can be lured to traps using synthetic sex attractants (Taft et al., 2004).
Wikipedia
See also Habitat Account for General Successional Fields and Forblands
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: GNR [S4S5]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.
Comments: Synanthedon rileyana appears to be common and widespread in North Carolina, but is only occasionally encountered in natural settings since it is not attracted to lights. It appears to be secure within the state.

 Photo Gallery for Synanthedon rileyana - Riley's Clearwing

Photos: 9

Recorded by: Kenneth Geisert on 2024-08-14
McDowell Co.
Comment: (CC BY-NC) (cropped)		Recorded by: elizamaeswallowtail on 2023-08-04
Person Co.
Comment: (CC BY-NC) (cropped and rotated)
Recorded by: Michael J. Papay on 2021-10-04
Macon Co.
Comment: (CC BY)		Recorded by: David George on 2021-08-09
Alamance Co.
Comment:
Recorded by: David George on 2021-08-09
Alamance Co.
Comment: 		Recorded by: David George on 2021-08-09
Alamance Co.
Comment:
Recorded by: Richard Teper on 2021-06-11
Orange Co.
Comment: 		Recorded by: Rob Van Epps on 2017-08-12
Mecklenburg Co.
Comment:
Recorded by: B. Bockhahn on 2011-07-29
Halifax Co.
Comment: