Helicoverpa zea, commonly known as the corn earworm, is a species (formerly in the genus Heliothis) in the family Noctuidae.

Since it is polyphagous (feeds on many different plants) during the larval stage, the species has been given many different common names, including the cotton bollworm and the tomato fruitworm.

Pupae can make use of diapause to wait out adverse environmental conditions, especially at high latitudes and in drought.

The corn earworm is found in temperate and tropical regions of North America, with the exception of northern Canada and Alaska as it cannot overwinter in these areas.

[4] They live in Kansas, Ohio, Virginia, and southern New Jersey, but survival rate is mainly affected by the severity of the winter.

[4] They are also found in Hawaii, the Caribbean islands, and most of South America, including Peru, Argentina, and Brazil.

[10] Once larvae have breached the chorion, they spend up to 83% of eclosion making an exit hole larger than their heads.

[15] This is because proper insulation facilitates development, and soil temperatures below 0 degrees Celsius correlate to higher pupal mortality.

Dehydration can also lead to high death rates among pupae, if soil moisture is as low as 1 to 2 percent.

[16] Adults have forewings that are yellowish brown in color and have a dark spot located in the center of their body.

[18] H. zea is the second-most important economic pest species in North America, next to the codling moth.

[8] Chemical control is widely successful, and includes the use of applying mineral oil inside the tip of each corn ear, which suffocates the young larvae.

[1][4] Corn earworm moths are not always vulnerable to the bacterium, and they are only afflicted by nematodes once the larvae have pupated and dropped to the ground.

[24] Some plants emit a blend of chemicals in response to damage from H. zea, which attract parasitic insects.

[25] Cardiochiles nigriceps, a solitary endoparasitoid wasp, makes use of these volatile plant compounds to identify the presence of H.

[25][26] The braconid wasp Microplitis croceipes, which deposits its eggs inside a living caterpillar, is also an important parasitoid of both H. zea and the related species Heliothis virescens.

[13] If the U. proteus begins to bite out of defense, H. zea rotates the larva 180° and uses its mandibles to puncture the head capsule, killing the insect.

[13] Then, the H. zea larva rotates the U. proteus back to its original position and continues feeding until the insect is entirely consumed.

[26] Helicoverpa zea is a seasonal, nocturnal migrant, and adults disperse, weather permitting, when there are poor reproductive conditions.

[20] Pupae have the ability to enter facultative diapause, the state of arrested development and growth in response to a change in the environment.

[30] Helicoverpa zea has a wide host range, attacking vegetables that include corn, tomato, artichoke, asparagus, cabbage, cantaloupe, collards, cowpea, cucumber, eggplant, lettuce, lima bean, melon, okra, pea, pepper, potato, pumpkin, snap bean, spinach, squash, sweet potato, and watermelon.

[32] Bore holes are observed in cabbage and lettuce hearts, flower heads, cotton bolls, and tomato fruits.

[35] About one-third of Virginia acreage is treated annually with insecticide, costing farmers around 2 million dollars.

Attacks that happen after August do much less damage because many pods have developed tougher walls that H. zea can't penetrate.

Infestations that affect pod formation and seed filling have the potential to reduce yields, and because this happens in the later stages of plants, they have less time to compensate.

[35] Heavy rainfall also decreases corn earworm populations because it drowns pupae in their soil chambers, limits moth flight, washes eggs from leaves, and creates favorable conditions for fungal diseases that kill caterpillars.

[37] Although the photoperiod regulates the release of PBAN to some extent, the chemical signals from the host plant supersede the effect from the time of day.

[39] The pheromonostatic peptide (PSP), a protein 57 amino acids long found in the male accessory gland, is what causes depletion of the female's sex pheromone.

[45] Helicoverpa zea males exposed to an attractive pheromone blend thus spend less time shivering and increase their heating rate.