Corn Earworm, Helicoverpa Zea

Helicoverpa zea (formerly in the genus Heliothis) is a serious agricultural pest. It is polyphagous in nature.

The larva is known as corn earworm, cotton bollworm and also tomato fruit worm. When the larva feeding cotton it is known as the cotton bollworm, when it feeding corn it is known as the corn earworm, and when it feeding tomatoes is known as the tomato fruit worm. It is distributed in throughout North America.

Russell IPM manufacture and supply pheromone lures, traps and complete monitoring systems for Corn Earworm, Helicoverpa zea. Pheromone trap data gives early warning of the infestation and also exhibits the density of the insect population.


Adult female lay eggs singly, usually on leaf hairs and corn silk. The egg is pale green when first deposited, becoming yellowish and then gray with time. The shape varies from slightly dome-shaped to a flattened sphere, and measures about 0.5 to 0.6 mm in diameter and 0.5 mm in height. Fecundity ranges from 500 to 3000 eggs per female. The eggs hatch in about three to four days. Upon hatching, larvae wander about the plant until they encounter a suitable feeding site, normally the reproductive structure of the plant. Young larvae are not cannibalistic, so several larvae may feed together initially. However, as larvae mature they become very aggressive, killing and cannibalizing other larvae. Consequently, only a small number of larvae are found in each ear of corn. Normally, corn earworm displays six instars, but five is not uncommon and seven to eight have been reported. Mature larvae leave the feeding site and drop to the ground, where they burrow into the soil and pupate. The larva prepares a pupal chamber 5 to 10 cm below the surface of the soil. The pupa is mahogany-brown in colours, and measures 17 to 22 mm in length and 5.5 mm in width. Duration of the pupal stage is about 13 days (range 10 to 25) during the summer. As with the larval stage, adults are quite variable in colour. The forewings of the moths usually are yellowish brown in colour, and often bear a small dark spot centrally. The moth measures 32 to 45 mm in wingspan. Adults are reported to live for five to 15 days, but may survive for over 30 days under optimal conditions. The moths are principally nocturnal, and remain active throughout the dark period. During the daylight hours they usually hide in vegetation, but sometimes can be seen feeding on nectar. Oviposition commences about three days after emergence, continuing until death. Fresh-silking corn is highly attractive for oviposition but even ears with dry silk will receive eggs. Fecundity varies from about 500 to 3000 eggs. Females may deposit up to 35 eggs per day (Credits: J. L. Capinera, 2002, University of Florida, UF/IFAS).

Nature of Damage

On corn, young larvae tend to feed on silks initially, and interfere with pollination, but eventually they usually gain access to the kernels. They may feed only at the tip, or injury may extend half the length of the ear before larval development is completed. Such feeding also enhances development of plant pathogenic fungi. If the ears have not yet produced silk, larvae may burrow directly into the ear. On tomato, larvae may feed on foliage and burrow in the stem, but most feeding occurs on the tomato fruit. Larvae commonly begin to burrow into a fruit, feed only for a short time, and then move on to attack another fruit. Tomato is more susceptible to injury when corn is not silking; in the presence of corn, moths will preferentially ovipositor on fresh corn silk. Other crops such as bean, cantaloupe, cucumber, squash, and pumpkin may be injured in a manner similar to tomato. (Credits: J. L. Capinera, 2002, University of Florida, UF/IFAS)


Russell IPM manufactures and supplies pheromone lure – the Qlure, traps and complete monitoring systems for Helicoverpa Zea, Corn Earworm.

Pheromone trap data gives early warning of the infestation and will also alert the user to a low level of population before it becomes serious.

The lure can be best applied with the Mothcatcher trap or Delta trap.

Lures for Pest Monitoring

Lures can be changed every 4-6 weeks to get the most accurate results.

Lures handling
Pheromone lures are a very sensitive tool. They can be affected by exposure to elevated heat and direct sunshine. Direct touching by hand may cause cross contamination leading to mixed catches in the trap. Some contaminants such as Nicotine May have repellent effect reducing trap catch.

Lure Storage

Store in a cool dry place. Shelf life can vary from 3-36 months depending on the storage temperature. See Technical Data Sheet for further details.

Trap Selection

The Deltra trap is the most sensitive trap to use for monitoring this insect. However, Moth catcher may be used in dusty conditions or in high moth population density.

Trap Density

Do not re-use the trap to monitor different insects as this may lead to mixed catches. One trap for every two hectares of large scale fields of homogenous lands.

Two traps per hectare (2trap/ha) for small holdings and in field of uneven topography.

Trap Position

Place traps near the highest point of the plant using supporting posts approximately 1 meter high, or higher if the crop is higher.

Data and Interpretation

Collect data weekly from the start of the flight of the over wintering generation. During the height of the population more frequent reading may be needed. Decisions on pesticide application should not be taken solely on the trap catch data. Climatic and biological considerations should be taken in account.

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