Corn Earworm Control: How to Identify, Prevent and Get Rid of Corn Earworms

Corn earworm or tomato fruitworm is the most devastating pest for corns in the United States. Knowing how to get rid of corn earworm is essential, especially for commercial growers, because of the massive damages that they can bring. It infests the product directly and after establishing itself, any control measure will no longer work. Prevention and early detection are critical.

This pest is a moth, which belongs to the noctuidae family. When they reach the stage of maturity, their color is usually light to dark brown and they have green eyes. They have stripes with alternating color in their body. They have wings that span from 1 to 1.5 inches. For males, the wings are usually light yellow. For females, on the other hand, it can be pink, brown, yellow, or a combination of such colors. In their larval stage, meanwhile, their length is one to two inches and the color varies on their instar stage. Lastly, their eggs start at a light color, but it darkens upon reaching maturity.

Corn Earworm on the Cob

A Corn Earworm is on the Cob

Corn Earworm’s Habitat

Corn earworm is common in the United States and is the greatest threat for corn. They thrive not only in commercial and large-scale plantations, but even in the garden. They start in the form of moths, after which, they lay their eggs, which hatch into caterpillars. They feed for an average of two weeks, and after this, they transform into a pupa.

These pests appear in the spring, although the specific time will depend on the climate and hardiness zone. There are some that appear as early as the last weeks of March, while there are others that do not emerge until August. In their search for food, they find their way in differ plants, which, in turn, becomes their breeding ground. Depending on the area where you live, this pest can have up to seven generation annually.

Identifying Corn Earworm’s Damage

Plants Affected

As the name implies, it is pretty much obvious that the most common plant where you can find this pest is in corn. In fact, in the United States, this is responsible for up to 2.5% of financial losses amongst corn growers. The same pest also grows in tomato, which is why they also go by the name tomato fruitworm. More so, they are also called cotton bollworm as they also grown in cotton plants. Other plants that they usually affect include soybeans, clover, pepper, and green beans.


The following are some of the symptoms you should watch out for, which will be indicative of the presence of corn earworms:

  • If the larva is the reason for the infestation, you will see holes on the leaves. They will be unattractive and will lessen the nutrition that the plant gets. However, in most cases, especially during the adult stage, they do not feed on the leaves, but directly in the crops. This leads to aesthetic damage, which renders the crop useless and unmarketable.
  • The appearance of insect secretions will also be indicative of the presence of corn earworms. This is especially the case of the nature pests. They leave yellow, red, or green discoloration on the surface of the plant where they are present. Remnants of longitudinal spines can also be present.
  • It is also common for other insects and pests to surround a plant where corn earworms are present. This is because the latter feed on the saps, which produce fermenting sugars. This odor attracts other pests.
  • In corn, they usually feed on the top 1/3 of the corn beginning on the ear. They do not destroy the cob, but they leave significant damages on the outer part of the corn. Fecal matter will also be present.

Results of Infestation

Loss of profits is perhaps the most common result of the damages from corn earworms. They do no feed on the leaves, but directly on the fruit. This means that the final output will carry the damages, and hence, make them unfit for human consumption. They can no longer be sold. Also, the larvae may deter growth and prevent pollination.

Corn Damaged

Corn Damaged by the Earworm

How to Get Rid of Corn Earworms

Natural and Organic Solutions

Below are some of the nontoxic solutions that aid in the elimination of corn earworms:

  • Using pheromone lures is one method that can work. They make use of pheromones, which, in turn, attract insects. Pheromone is the fragrance from a female insect, which attracts males. They are available in commercial products with a sticky surface so that the pests will not have any escape.
  • Attracting beneficial insects in the garden is another promising solution. Some of the best examples of the latter include damsel bugs, minute pirate bugs, and green lacewings. These insects, however, will only be effective in the elimination of eggs and young larva. Upon reaching maturity, they will no longer help.
  • The release of beneficial nematodes will also help. Do this just in time before the first frost and make sure that the soil is moist.
  • You can also consider using sprays that contain bacillus thuringiensis. The latter is common in insect sprays, but the good thing is that it is nontoxic, unlike the chemical solutions. They are organic and kill only the pests. However, keep in mind that this solution is only for larva.

Chemical Solutions

Chemical sprays are promising in protecting crops from damage. However, keep in mind that there are some active ingredients that won’t work because of the resistance of the pest. For instance, those in the carbamate family will most likely not yield successful outcomes. Look for synthetic pyrethroids as they are the most effective.

How to Prevent Corn Earworms

Preventive management as early as possible, preferably once the ears have as much as 10% silk. Spraying a solution is best until the appearance of at least 90% of the silk. This will provide you with the guarantee that the plant will be worm-free until the time of harvest. If you do not want to resort to the use of sprays with toxic chemicals, mineral oil spray is a promising solution. Farmers apply it on the ear, but this can be a tedious job and can lead to an unpleasant taste.

Early planting of crops, especially corn, is another preventive measure. As much as possible, harvest the corn just before August. Aside from this, another cultural control measure is planting the right variety, specifically those that are more tolerant and resistant.

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