Moths of North Carolina
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View PDFCrambidae Members: Neodactria Members: 15 NC Records

Neodactria caliginosellus (Clemens, 1860) - Corn Root Webworm Moth

Neodactria caliginosellusNeodactria caliginosellus
Taxonomy
Superfamily:
Pyraloidea		 Family:
Crambidae		Subfamily:
Crambinae		Tribe:
Crambini		P3 Number:
80a1511		 MONA Number:
5381.00		 Other Common Name:
Black Grass-veneer
Comments: The genus Neodactria contains several closely related forms that comprise a species complex that is poorly resolved. Members of this group, including N. luteolellus, N. caliginosella and N. zeella, can often be identified by coloration and patterning, but there appears to be much overlap in variation of external characters between the members of the complex, at least across the entire ranges of these species. There is currently a general lack of consensus among taxonomists as to the number of species that should be recognized. As Brian Scholtens (2017) noted concerning the species in the southeastern U.S., "These may or may not be distinct species. There is a great deal of variation in coloration and pattern, so that no clear groups can be easily defined." A comprehensive study of this species complex across the U.S. and Canada is needed. Our assignment of specimens to species is based on the original descriptions of the species and other evidence.
Species Status: This species was a significant pest on tobacco and corn prior to the use of modern insecticides (Runner, 1914).
Identification
Field Guide Descriptions: Online Resources: MPG, BugGuide, iNaturalist, Google, BAMONA, GBIF, BOLDTechnical Description, Immature Stages: Runner (1914).                                                                                 
Adult Markings: In this species the head, thorax, and palps are dark fuscous and dusted to varying degrees with gray scales (Fernald, 1896). The ground color of the forewings is dark fuscous or orangish-fuscous with a sprinkling of brown and yellow scales, and usually with a scattering of gray scales. The median and subterminal lines are often only weakly developed. They are often either blackish and margined with white, or orangish-fuscous and overlain with varying levels of dark brown to blackish scales. The median line originates at the costa and forms a sharp angle at the end of the cell, then runs obliquely to the inner margin, with an outward tooth or angle at the fold. The subterminal line is similar in color and runs roughly parallel to the median line, but is irregularly jagged and often has four or five small blackish teeth. In some of our specimen, there is a pale gray patch between the two lines that extends to the inner margin. The terminal line is usually very narrow and indistinct, while the fringe is a dark, leaden gray. The hindwings are dark fuscous with lighter fringes.

Both Neodactria luteolellus and N. zeelus are similar in form and forewing pattern but the ground color of the forewings is mostly ocherous yellow in N. caliginosellus and ashy gray in N. zeelus (Fernald, 1896). Both N. luteolellus and N. caliginosella lack the two narrow, pale ocherous lines seen in N. zeelus that run longitudinally out from the wing base.
Wingspan: 13-25 mm (Fernald, 1896); 13-20 (Ainslie, 1924).
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 following life history account is based on Runner (1914), who studied the larvae as pests in corn and tobacco fields in Virginia. Additional observations were made on weedy plants that served as hosts such as Oxe-eye daisy and Queen-Anne's-lace. In this study the adults first emerged in late-June and peaked during the first half of September. They were active shortly before dark and into the early evening, and the females deposited their dry eggs from the air as they flew over potential host plants. Females produced an average of 177 eggs that were initially white, but turn orange-rufous before hatching. Hatching required 4-7 days, and the larvae fed on the roots and stem bases of the host plants.

Runner (1914) noted that a single plant often had several larvae on it (up to 20 larvae per plant on Queen-Annes-lace). The hatchlings typically began feeding just below the ground surface and frequently entered the stalk and produced feeding galleries. When not feeding they resided in cylindrical, web-lined shelters that often extended several centimeters away from the plant below ground. The larvae often girdled young corn and tobacco plants, and the injured plants frequently wilted or become stunted. The full-grown larvae averaged around 15 mm in length and were yellowish-white with a tinge of pink dorsally, with large, fuscous pinacula. The head shield was pale yellowish-brown and flecked with darker brown, the prothoracic shield was shiny yellowish-brown, and the anal shield was pale fuscous. The larvae pupated in the soil, and usually within 2-15 cm of the base of their host plant. Pupation occurred in cocoons that were made of silk and soil particles and that were 3-10 cm deep depending on the soil texture. The adults emerged after 10-15 days. Local populations of this species are typically univoltine, with the larvae from the new brood overwintering in the soil, then resume feeding the following spring.
Distribution in North Carolina
Distribution: Neodactria caliginosellus is primarily found in the eastern U.S. and adjoining areas of southern Canada, but scattered records are known from a few western states, including California, Montana and Colorado. This species occurs in Canada from the Northwest Territories and British Columbia eastward to Nova Scotia and Prince Edward Island. In the U.S. the range extends from Maine southward to southern Florida, and westward to Alabama, Tennessee, Kentucky, Illinois and Indiana. As of 2023, our records are restricted to the Piedmont and the Blue Ridge.
County Map: Clicking on a county returns the records for the species in that county.
Neodactria caliginosellusAlamance Alexander Alleghany Anson Ashe Avery Beaufort Bertie Bladen Brunswick Buncombe Burke Cabarrus Caldwell Camden Carteret Caswell Catawba Chatham Cherokee Chowan Clay Cleveland Columbus Craven Cumberland Currituck Dare Davidson Davie Duplin Durham Edgecombe Forsyth Franklin Gaston Gates Graham Granville Greene Guilford Halifax Harnett Haywood Henderson Hertford Hoke Hyde Iredell Jackson Johnston Jones Lee Lenoir Lincoln Macon Madison Martin McDowell Mecklenburg Mitchell Montgomery Moore Nash New%20Hanover Northampton Onslow Orange Pamlico Pasquotank Pender Perquimans Person Pitt Polk Randolph Richmond Robeson Rockingham Rowan Rutherford Sampson Scotland Stanly Stokes Surry Swain Transylvania Tyrrell Union Vance Wake Warren Washington Watauga Wayne Wilkes Wilson Yadkin Yancey
Flight Dates:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

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