Moths of North Carolina

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Achyra rantalis (Guenée, 1854) - Garden Webworm Moth

Taxonomy

Superfamily:
Pyraloidea

Family:
Crambidae

Subfamily:
Pyraustinae

Tribe:
Pyraustini

P3 Number:
80a0742

MONA Number:
4975.00

Identification

Field Guide Descriptions: Covell (1984); Beadle and Leckie (2012)

Online Resources: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLD

Technical Description, Adults: Munroe (1976)

Technical Description, Immature Stages: Capps (1967)

Adult Markings: The following description is based mostly on those of Capps (1967) and Munroe (1976). The ground color of the forewing can be various shades of orange, brown or fuscous, with the marking slightly darker than the ground color. The reniform spot is conspicuous and much larger than the orbicular spot. The antemedial line is rather smooth and irregularly angulated, while the postmedial line is denticulate and bowed outward on the costal two-thirds. Both lines can be rather weak and diffuse. The post-medial line is often shaded on the outer margin with a thin line of lighter color, and the area between the postmedial line and the termen is often lighter than the general ground color. The terminal line is broken and consists of a line of 7-8 dark spots. The hindwing is often paler than the forewing and the postmedial line, if evident, is diffuse. Females are usually somewhat darker than the males and tend to have stronger markings.

Wingspan: 17 -23 mm (Capps, 1967)

Forewing Length: 9-10 mm (Powell and Opler, 2009).

Adult Structural Features: Capps (1967) has descriptions and illustrations of the male and female genitalia.

Structural photos

Adult ID Requirements: Identifiable from good quality photos of unworn specimens.

Immatures and Development: The larvae feed on numerous species, including many cultivated plants. The following is a summary of the life history based on Smith and Franklin’s (1954) studies in alfalfa fields in Kansas. The larvae web together the terminal leaves of the main stems and lateral branches to form nests, then feed internally on the leaves. Females deposit their eggs in flat scale-like masses of up to 37 eggs. The hatchlings feed together during the first instar, then disperse to the tops of plants and web together leaves to make nests. The first two instars skeletonize the leaves, while the latter instars consume entire leaves and produce copious amounts of black frass that clings to the webbing. The larvae pass through six instars. When fully grown, they drop to the ground and spin silk cocoons that extend vertically or nearly so just below the surface of the soil. The brownish pupal cases are around 12-13 mm long and are thin, flat, and nearly transparent. They have an open end that faces towards the soil surface that allows the adult to emerge. The pupal stage lasts around 10 days, and the adult crawl up plants soon after they emerge and dry their wings. In Kansas, populations passed through three generations and overwintered as pupae.

The final instar larvae are around 24-25 mm long. The body ground color varies from greenish to brown or nearly black, and there is a narrow mid-dorsal stripe. The head is pale and has netlike amber markings and a fuscous patch on each side at the incision of the posterior margin. The prothoracic shield has two dark bars on each side. The pinacula appear as bold, black spots above the level of the spiracles, while those below the spiracles have pale centers and appear ring-like (or Capps, 1967; Munroe, 1976). Each body segment has three black spots on each side that are arranged in a triangular pattern.

Larvae ID Requirements: Identifiable from good quality photos, especially where associated with known host plants.

Distribution in North Carolina

Distribution: This is a very wide-ranging species that is found in almost every state in the conterminous U.S. except Wyoming, North Dakota and Montana, as well as in Canada (Ontario; Quebec; Nova Scotia), the West Indies and Mexico. As of 2023, all of our records are from the Piedmont and Coastal Plain.

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: As of 2023, we have records from late-March through late-September. Populations in the Coastal Plain are bivoltine, but those in other states such as Kansas and Oklahome can have 3-5 generations per year (Smith and Franklin, 1954) .

Habitats and Life History

Habitats: Local populations are commonly found around crop fields, home gardens, road corridors and other disturbed settings.

Larval Host Plants: The larvae are polyphagous and feed on both cultivated and non-cultivated plants (Smith and Franklin (1954), Capps, 1967; Covell, 1984; Heppner, 2007; Robinson et al., 2010). They commonly feed on garden vegetables and cultivated crops such as alfalfa, amaranths, beans, black-eyed peas, clover, corn, cotton, cowpeas, radishes, soybeans, strawberries, sunflowers, sugar beets and Swiss chard. Other hosts include pigweeds (Amaranthus), Giant Ragweed (Ambrosia trifida), Common Ragweed (A. artemisiifolia), Spearscale Orache (Atriplex patula), Turtleweed (Batis maritima), Lambsquarter (Chenopodium album), guayule (Parthenium argentatum), smartweeds (Polygonum), roses (Rosa), docks (Rumex), sea-purslane (Sesuvium), thistles and undoubtedly many other kinds of weeds. - View

Observation Methods: The adults are attracted to lights, and the larvae are commonly found in vegetable garden and commercial field crops.

Wikipedia

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: This wide-ranging species is common in the eastern half of the state and appears to be secure, in part due to its use of cultivated and weedy plants as a food source.

Photo Gallery for Achyra rantalis - Garden Webworm Moth

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

	Recorded by: Mark Basinger on 2025-11-07 Brunswick Co. Comment:		Recorded by: Mark Basinger on 2025-08-24 Brunswick Co. Comment:
	Recorded by: Mark Basinger on 2025-07-22 Brunswick Co. Comment:		Recorded by: Mark Basinger on 2025-07-21 Brunswick Co. Comment:
	Recorded by: Mark Basinger on 2025-06-02 Brunswick Co. Comment:		Recorded by: Dean Furbish and Joy Wiggins on 2025-05-01 Pender Co. Comment:
	Recorded by: Dean Furbish on 2025-04-29 Pender Co. Comment:		Recorded by: Dean Furbish and Joy Wiggins on 2025-04-28 Pender Co. Comment:
	Recorded by: Dean Furbish and Joy Wiggins on 2025-04-27 Pender Co. Comment:		Recorded by: Mark Basinger on 2025-04-24 Brunswick Co. Comment:
	Recorded by: John Petranka, Jim Petranka, Becky Elkin on 2025-04-14 Bladen Co. Comment:		Recorded by: R. Newman on 2024-12-09 Carteret Co. Comment:
	Recorded by: Mark Basinger on 2024-08-31 Brunswick Co. Comment:		Recorded by: Michael P. Morales on 2024-08-29 Cumberland Co. Comment:
	Recorded by: Michael P. Morales on 2024-08-29 Cumberland Co. Comment:		Recorded by: Lior S. Carlson, Dean Furbish on 2024-08-13 Pamlico Co. Comment:
	Recorded by: Dean Furbish, Lior S. Carlson on 2024-08-12 Pamlico Co. Comment:		Recorded by: Dean Furbish, Lior S. Carlson on 2024-08-12 Pamlico Co. Comment:
	Recorded by: R. Newman on 2024-08-09 Carteret Co. Comment:		Recorded by: R. Newman on 2024-07-11 Carteret Co. Comment:
	Recorded by: Hunter Phillips on 2024-06-21 Onslow Co. Comment:		Recorded by: Dean Furbish on 2024-06-07 Wake Co. Comment:
	Recorded by: Mark Basinger on 2024-05-25 Brunswick Co. Comment:		Recorded by: Dean Furbish on 2024-05-09 Pender Co. Comment:
	Recorded by: Mark Basinger on 2024-04-28 Brunswick Co. Comment:		Recorded by: Mark Basinger on 2024-04-21 Brunswick Co. Comment:
	Recorded by: Mark Basinger on 2024-04-21 Brunswick Co. Comment:		Recorded by: Mark Basinger on 2023-09-30 Brunswick Co. Comment:
	Recorded by: Mark Basinger on 2023-09-03 Brunswick Co. Comment:		Recorded by: Mark Basinger on 2023-08-18 Brunswick Co. Comment: