Moths of North Carolina
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14 NC Records

Synanthedon decipiens (Edwards, 1881) - Oakgall Borer Moth

Synanthedon decipiensSynanthedon decipiensSynanthedon decipiensSynanthedon decipiens
Taxonomy
Superfamily:
Sesioidea		 Family:
Sesiidae		Subfamily:
Sesiinae		Tribe:
Synanthedonini		P3 Number:
55a0114		 MONA Number:
2571.00		 Other Common Name:
Oak Gall Borer
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: Online Resources: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Engelhardt (1946)Technical Description, Immature Stages: MacKay (1968)                                                                                 
Adult Markings: Synanthedon decipiens is best identified by a combination of traits, including a black head, yellow collar, black thorax that lacks yellow lateral bands, an orange to reddish discal spot, and an abdomen with yellow banding on segments 2, 4, 6, and 7, with segment 4 noticeably broader than the others. The following detailed description of the male is based on descriptions by Engelhardt (1946) and Eichlin and Duckworth (1988).

The antenna is black and often powdered with yellow on the basal half. The labial palp is strongly roughened and golden-yellow, with black on the first segment that extends laterally onto most of the second segment. The vertex of the head is black, the collar yellow, and the front black with white laterally. The thorax is black with a large yellow patch beneath each wing. The posterior margin has a yellow, transverse band and lateral yellow tufts that create a broad band that resembles one on the abdomen. The abdomen is black, with a narrow yellow band on segments 2, 6, and 7, and a broad band on segment 4. Segments 1 and 2 have yellow along the sides, and segment 4 is the only segment that is banded with yellow underneath. The anal tuft is wedge-shaped and mostly black, with a whitish to yellowish edge. The legs are broadly banded with yellow and black, and most conspicuously so on the hindleg. The forewing is mostly transparent, with the costa heavily scaled, and with a mix of black and orange scales. The veins are black, with the area between the veins below the outer margin dusted with orange. The discal spot is orangish-red, the fringes brown, and the underside heavily shaded with golden-yellow. The hindwing is transparent with very narrow margins, and has a discal spot that is very small and orange.

The females are generally similar to the males, but differ in having broader wing margins and denser orange shading between the veins, including on the basal half. The discal mark is bright red, and the abdomen has a narrow yellow band on segments 2 and 6, with the band on segment 4 twice as broad as those on segments 2 and 6. The anal tuft is short, rounded, and black with a yellow edge.
Wingspan: 15-17 mm for males and 15-18 for females.
Forewing Length: 8-10 mm (Eichlin and Duckworth, 1988).
Adult Structural Features: Eichlin and Duckworth (1988) provide descriptions of the male and female genitalia, and MPG has an illustration of the male genitalia (also see below).
Structural photos
Adult ID Requirements: Identifiable from photos showing hindwings, abdomen, or other specialized views [e.g., frons, palps, antennae, undersides].
Immatures and Development: The larvae are borers in various species of oaks. Although they will bore into the trunks or branches, they show a strong tendency to use the galls of cynipid wasps that form on oak twigs. Engelhardt (1946) reported that they invade galls that are hard and woody and avoid those that are soft and spongy. Galls that are preferred are mature, but still retain sufficient living tissue to support the borers through their life cycle. After emerging and mating, the females lay eggs on either the bark or on the surface of galls, particularly those in the genus Andricus. The hatchlings bore into the bark or galls and produce extensive cavities that contain reddish frass. When mature, the larvae pupate in silk-lined cells that are constructed in the pithy interior of the galls (Engelhardt, 1946; Solomon, 1995). At emergence, the pupae break through the outer wall of the gall and the adult emerges shortly thereafter. Populations in southern states such as Georgia appear to have two broods per year, with peak catches of adults in April and May and again in August and September (Snow et al., 1985). Larvae from the second brood overwinter, with the adults emerging the following spring. Populations in the north appear to have a single brood, with the larvae overwintering and the adults emerging the following spring or summer after completing a life cycle that last about one year.
Distribution in North Carolina
Distribution: Synanthedon decipiens is widely distributed throughout most of the eastern US and in adjoining areas of southern Ontario and Quebec. The range in the US extends from New Jersey and Maryland southward along the Atlantic Seaboard states to central Florida, and westward to central Texas, eastern Oklahoma, Missouri, Illinois, Iowa, Wisconsin and Minnesota. Scattered records are also known from Colorado, southeastern New Mexico, western Texas and northeastern Mexico. This species is largely absent from much of the Appalachian Mountains. As of 2024, all of our records are from the eastern Piedmont and Coastal Plain.
County Map: Clicking on a county returns the records for the species in that county.
Synanthedon decipiens
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 found from March through November in different areas of the range. Southern populations have long flight seasons and appear to have two broods per year, while northern population produce a single brood and fly mostly from May through July. As of 2024, our records are from mid-April through early-October. Populations in North Carolina appear to produce at least two broods, and perhaps a partial third, with the first flight from April through early-May, and the second from early-July through early-October.
Habitats and Life History
Habitats: Local populations are associated with forests with oaks, and often at sites that vary from moderately dry to xeric.
Larval Host Plants: The larvae feed on oaks, both as borers in the trunks and limbs, but far more commonly in the galls of cynipid wasps that form on oak trees (Engelhardt, 1946). The known hosts include Water Oak (Quercus nigra), Pin Oak (Q. palustris), Black Oak (Q. velutina), Live Oak (Q. virginiana), along with 'scrub' oaks (species not specified) in Florida and Alabama. - View
Observation Methods: The adults are mostly diurnal, but have occasionally been collected in light traps. They can be found resting on vegetation or nectaring on goldenrods or other wildflowers during the day. The moths are attracted to pheromone traps, and the adults can be reared by harvesting oak galls in the spring or early summer.
Wikipedia
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: GNR [S2S3]
State Protection:
Comments: Synanthedon decipiens is uncommon in North Carolina, perhaps because of its reliance on oak galls as a larval food source. More information is needed on its host plants, distribution and abundance before we can accurately assess its conservation status.

 Photo Gallery for Synanthedon decipiens - Oakgall Borer Moth

Photos: 5

Recorded by: iheartmollusks on 2023-10-04
Dare Co.
Comment: (CC BY-NC) (cropped)		Recorded by: hagfish on 2023-09-08
Dare Co.
Comment: (CC BY-NC) (cropped)
Recorded by: emheinz on 2023-04-14
Wake Co.
Comment: (CC BY-NC) (cropped)		Recorded by: Mark Shields on 2019-09-30
Onslow Co.
Comment:
Recorded by: J.B. Sullivan on 2017-08-15
Carteret Co.
Comment: