Synonyms and other taxonomic changes
First described in 1850 by John W. Boddie as Phalaena zea
Heliothis zea
Helicoverpa zea
Explanation of Names
zea is the scientific name for corn/maize
Size
Larval length 1.5 - 24.8 mm
Adult wingspan 32 - 45 mm
Identification
Adult: forewing dull yellowish, usually with diffuse grayish shading in subterminal area (sometimes absent); PM line scalloped, with dots at the tips of the scallops; median line thin, straight; AM line scalloped (but in opposite direction as PM line, with dots at the
bases of the scallops); orbicular spot* buff-colored, round, with central dark dot; reniform spot a dark gray blotch; terminal line a series of dark dots; all of these markings (except the reniform spot) may be very faint in some individuals, as in
this example; hindwing white with prominent dark veins and broad blackish terminal band surrounding small pale patch mid-way along outer margin; fringe pale yellow (
see pinned adult photo at CBIF).
*The circular buff orbicular spot with dark central dot is recognizable and diagnostic in most images.
"The larva is variable in color. Overall, the head tends to be orange or light brown with a white net-like pattern, the thoracic plates black, and the body brown, green, pink, or sometimes yellow or mostly black. The larva usually bears a broad dark band laterally above the spiracles, and a light yellow to white band below the spiracles. A pair of narrow dark stripes often occurs along the center of the back. Close examination reveals that the body bears numerous black thorn-like microspines. These spines give the body a rough feel when touched." -
Featured Creatures
"As with the larval stage, adults are quite variable in color. The forewings of the moths usually are yellowish brown in color, and often bear a small dark spot centrally. The small dark spot is especially distinct when viewed from below. The forewing also may bear a broad dark transverse band distally, but the margin of the wing is not darkened. The hind wings are creamy white basally and blackish distally, and usually bear a small dark spot centrally." -
Featured Creatures
Adult moth's eyes are green.
Range
Throughout North America except northern Canada and Alaska.
Food
Larvae feed on a wide range of hosts, including many field crops, hence this species has been much studied.
Adult moth feeds on nectar, especially of trees and shrubs.
Life Cycle
Once a host plant is identified, pheromone production and its release begins. Calling behavior appears to be elicited by volatiles from the corn ear silk.
(1)
Females lay more eggs on the upper, hairy surface of the corn leaf than on the glabrous underside. They either grasp a leaf vein or a surface hair. On millet, they lay 10x as many eggs on the more pubescent leaves.
(2)
Volatiles release from corn silks set off the synthesis of the female sex pheromone, which attracts the male. Ethlyene is the main plant ripening hormone that triggers this; it is mixed with other corn volatiles, too.
(3)
Larva; larva; larva; pupa; adult
Remarks
Tricosane, a chemical from corn plants, appears on the eggs. This chemical becomes a kairomone for the egg parasitoid,
Trichogramma evanscens.
(4)See Also
Adult
Copablepharon species lack the lines and other markings mentioned in the above description (
see photos of 3 species at CBIF).
Female
Paradoxical Grass Moth,
Heliocheilus paradoxus, is superficially similar but is much smaller (FW 11-13 mm) and has a more rounded FW costal margin.
Larvae of
Spodoptera frugiperda and
Ostrinia nubilalis also feed on corn, but both have a dark head, and lack microspines.
Internet References
Moth Photographers Group - photos of living and pinned adults.
Corn Earworm - University of Florida provides a detailed species account including photos.
Southern Cultivator, v.8, p.132 Boddie's original description of the species (Google Book)
