Moths of North Carolina
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28 NC Records

Vitacea polistiformis (Harris, 1854) - Grape Root Borer Moth

Vitacea polistiformisVitacea polistiformisVitacea polistiformisVitacea polistiformis
Taxonomy
Superfamily:
Sesioidea		 Family:
Sesiidae		Subfamily:
Sesiinae		Tribe:
Paranthrenini		P3 Number:
55a0065		 MONA Number:
2530.00
Comments: North America has 136 or more species in the family Sesiidae, with 37 species found in North Carolina. Many are similar in appearance to one another, and some are significant pests of commercial crops. Almost all of our species are mimics of wasps and hornets.
Species Status: Vitacea polistiformis has been a major pest in grape vineyards for decades. The larvae bore into the root stocks and roots and can weaken or kill the plants. Despite much research on this species, it continues to be a major pest.
Identification
Field Guide Descriptions: Covell (1984)Online Resources: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Adults: Eichlin and Duckworth (1988)                                                                                 
Adult Markings: Vitacea polistiformis is a mimic of two rust-colored paper wasps (Polistes carolina; P. perplexus) that occur in the eastern US. This species has dark forewings and an overall rusty-brown appearance. The abdomen has two thin yellowish bands, and the males have four prominent pencils that extend from the tip of the abdomen. The following detailed description of the male is based on that of Engelhardt (1946) and Eichlin and Duckworth (1988).

The antennae is bipectinate and orange with varying amounts of brownish-black scaling dorsally. The labial palp is red-brown, with brown or black at the base and along the sides. The head is brown above and the face shiny whitish to pale, with the occipital fringe deep orange. The collar is black with pale yellow at the sides. The thorax is brownish-black above, with rufous coloration along the sides and yellowish to yellowish-orange scaling near the anterior margin, in front and beneath the wing bases, and on the posterior margin. The forewing is opaque and brownish-black except for a small hyaline area near the wing base and rust-red scaling along the base of the inner margin. The hindwing is mostly hyaline with brownish-black scaling along the veins and wing margin that widens at the anal angle. The abdomen varies from brown to brownish-black and often has lighter brown on segments 5-7. A very narrow yellow band is on the posterior margin of segments 2 and 4, and often as a slightly visible one on segment 6. The anal tuft is short, blunt, and brownish-black. It has four orange-brown pencils, with the dorsal two longer than those on the sides. The tibia and tarsi are uniformly orangish. The female is generally similar to the male, but has a simple blue-black antenna with a rufous tip, a thorax with yellow stripes laterally and transversely on the metathorax, and a dark chestnut-brown abdomen that is much larger than that of the male.

Vitacea scepsiformis is very similar to V. polistiformis but has an elongated, triangular, dark streak on the hindwing that extends inward from the middle of the outer margin (missing on V. polistiformis), brownish-black scaling on the hind tibia (versus pure orange for V. polistiformis), and a single yellowish abdominal stripe on segment 2.
Wingspan: Males 26-30 mm; female 36-42 mm (Engelhardt, 1946).
Forewing Length: 12-19 mm (Eichlin and Duckworth (1988).
Adult ID Requirements: Identifiable from good quality photos of unworn specimens.
Immatures and Development: The larvae are major pests in grape vineyards and several detailed studies of the life history have been published beginning more than a century ago (e.g., Brooks, 1907; Clark and Enns, 1964; Dutcher and All, 1979). The following summary is largely based on a review by Rijal and Bergh (2017). The larvae pupate in the soil around the base of grape vines and the adults emerge during the late-morning hours. Mating typically occurs in the afternoon on warm, sunny days. Females deposit their eggs singly on the grape leaves, vines, or nearby weeds and can lay from 350–500 eggs over a 7–8 day period. Many of the eggs may drop to the ground before the larvae hatch, with development to hatching taking around two weeks. The hatchlings are white with a brown head capsule, and immediately burrow into the ground and search for grape roots. After reaching a root, they bore into the root cortex and create feeding channels packed with reddish frass that increase in diameter as the larvae mature (Dutcher and All, 1979). A single root system can have a dozen or more larvae that eventually tend to move toward the crown of the vine during their development. The larval period can take 1-3 years depending on local climates and environmental conditions, and typically 1-2 years in North Carolina (NC State Extension Publications). The mature larvae are whitish and grub-like and grow to as much 30 mm long and 6 mm wide. The final-instars eventually leave their galleries and pupate in the soil within cocoons that are constructed of soil, frass, and silk. After 29-33 days of development, the pupae leave their cocoon and make their way to the soil surface where the adults emerge.
Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.
Distribution in North Carolina
Distribution: Vitacea polistiformis is widely distributed across the eastern US where the range extends from Massachusetts and southern New York southward to southern Florida, and westward to central Texas, central Oklahoma, central Kansas, central Nebraska, Wisconsin and southern Minnesota. There are also records from adjoining areas of Ontario. This species appears to occur statewide in North Carolina, but records are lacking for the northern Coastal Plain and much of the Blue Ridge as of 2024.
County Map: Clicking on a county returns the records for the species in that county.
Vitacea polistiformis
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 mostly fly from May through September, but the flight season varies substantially with latitude. In Florida, adults have been observed from early-May through December, while in the northern part of the range the flight season may only last two months. In Virginia, the adults emerge from late-June until about early-September, with peak emergence between late-July and early-August. As of 2024, our records range from mid-May through late-August.
Habitats and Life History
Habitats: Local populations are commonly found in vineyards and in natural communities where native grapes abound. Engelhardt (1946) noted that low-growing vines in open country are preferred over climbing vines in woodlands.
Larval Host Plants: The larvae feed on numerous types of cultivated grapes, but information on the use of native grapes is sparse. Engelhardt (1946) reared the adults from Fox Grape (Vitis labrusca), and this species attacks Muscadine (Muscadinia rotundifolia) and bunch grapes in vineyards in North Carolina (Poling et al., 2003). Although undocumented, other native grapes are undoubtedly used in North Carolina and elsewhere. - View
Observation Methods: The adults are occasionally spotted resting on vegetation in or near grapes and can be readily attracted using pheromone traps.
Wikipedia
See also Habitat Account for General Vitaceous Tangles
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: GNR [S3S4]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands.
Comments: This species is very likely more widespread and abundant than our records suggest; it can be locally abundant in grape vineyards throughout the state.

 Photo Gallery for Vitacea polistiformis - Grape Root Borer Moth

Photos: 8

Recorded by: Rob Van Epps on 2024-07-22
Mecklenburg Co.
Comment: 		Recorded by: David L. Heavner on 2024-05-19
Chatham Co.
Comment:
Recorded by: David L. Heavner on 2024-05-19
Chatham Co.
Comment: 		Recorded by: Rob Van Epps on 2023-08-13
Mecklenburg Co.
Comment:
Recorded by: Simpson Eason on 2020-08-14
Durham Co.
Comment: 		Recorded by: Simpson Eason on 2020-08-14
Durham Co.
Comment:
Recorded by: Jim Petranka and Becky Elkin on 2019-08-09
Madison Co.
Comment: 		Recorded by: B. Fleming on 2014-08-16
Carteret Co.
Comment: