Corn Rootworm Control: How to Identify, Prevent and Get Rid of Corn Rootworms

Belonging to the genus of Diabrotica, corn rootworm affects a variety of corn species. Whether in the form of adults or larvae, they can bring damages in more ways than one. They will feed on the different parts of the plant and can cause a severe infestation. This makes it critical to be aware of how to get rid of corn rootworms so that they won’t be too much of a problem.

The physical appearance of corn rootworms may vary depending on its specific type, although most of the damages they cause will be similar. The Western Corn Rootworm has a yellow body with dark stripes. The male rootworm from this type is usually smaller and darker. The Northern Corn Rootworm, on the other hand, has a green to yellow body and the female is usually the one that is larger. It has an average length of ¼ inch. Lastly, the Southern Corn Rootworm has a green body that is easy to distinguish because of the black spots on its back. With the way it looks, there is no wonder why it is also called spotted cucumber beetle.

Corn Rootworm Larva

Western Corn Rootworm Larva

Corn Rootworm’s Habitat

This pest is common to what is called the Corn Belt of the United States. The different types thrive in different places, although most of the infestation takes place in Northern America. Whether in the form of adults or larva, they will grow in plantations with maize. Records state that they can survive in more than 280 plant species. They often feed on the roots of their host. Most of them love wet soil, which is why they are common in the spring as they love moist or damp places. They will attack the plant when it is still young.

Identifying Corn Rootworm’s Damage

Plants Affected

The main host plant of this pest is corn. However, it will also damage other root crops, which include squash, clover, alfalfa, and cucumber. It also affects flowers, grass, and weeds.


Pay attention to the following signs, which will give you a warning that corn rootworms are present:

  • One of the most common symptoms of corn rootworm is root rot. This results from the creation of tunnels in the roots, which attracts pathogens and will eventually damage the plant. It also compromises the capability of the plant to absorb nutrients.
  • With the damage to the roots, this will also weaken the foundation of the plant. It affects the stability of the plant, making it fall. This becomes even a bigger problem if the soil is moist and if there is a strong wind.
  • Silk clipping is another sign of damage that will be evident. It causes damages on the tip of the ear, which does not only result to cosmetic damage, but can also restrict the flow of nutrients.
  • Taking a look at the crop yield will also show symptoms of corn rootworm, especially when it affects plants in the later stages. It will lead to the reduction of kernel production. Kernels may also end up being flat.

Results of Infestation

Whether they are in their adult or larval stage, they can cause heavy infestation on their host plants. The larva will mostly damage the roots, resulting in an opening in the tunnels. This inhibits the growth of the plant as it blocks the nutrients that are necessary for a healthy growth. Silk damage in corn is another common result of damage from this pest. They will also cause the wilt bacteria to spread, which will make the plant weaker.

Corn Rootworm Damage

Corn Rootworm Larval Root Injury

How to Get Rid of Corn Rootworms

Natural and Organic Solutions

If you are looking for the best ways to control corn rootworm in a manner that is natural and safe, the following are some of the most common methods that will work:

  • Among others, one thing that you can do is to place covers on the top of your plants. This will work best with squash and beans, among others. With the cover, the plants will have protection from the pest. However, take note that this is not a long-term solution. For pollination, you need to remove the cover.
  • If you only have a small garden, one solution that will be effective is hand-picking them. Learn their physical characteristics, which will make it easy to spot their presence. Take them out of the plant manually. Throw the worms in a bucket with soapy water, which will kill them. Also, look for eggs and remove them from the plant before they even hatch.
  • Biological control is another solution that proves to be promising. This will be an ideal solution if the corn rootworm is still young. You can either purchase them or alter the external environment to make it more attractive for natural predators. Some of the best choices include tachinid flies, ground beetles, and birds.
  • Cultivation is another thing that can prove to be effective. This is not only good for an elimination of corn rootworms, but also for their prevention. This will make the garden clean and it will also kill the eggs that overwinter on the ground.
  • For a simpler solution, you might also want to consider using sticky traps. Just place the trap on the ground and leave it for the night. The morning after, you will see a concentration of worms. Make sure to throw it properly so that the corn rootworm will not go back to its host.

Chemical Solutions

For large plantations and heavy infestation, chemical control is a common choice. There are different active ingredients that will target the corn rootworm. The problem, however, is that they can be toxic to other insects as well, including those that act as natural predators. Among other insecticides, one of the best is Lorsban 15G, which contains chlorpyrifos. Terbufos, which is an active ingredient in Counter 20CR, can also deliver a high level of effectiveness.

How to Prevent Corn Rootworms

The best way to deal with corn rootworms is to prevent it. One of the best things that can be done is crop rotation. The right planting time is also a preventive measure that will work. As much as possible, plant the crop early. It will be more attractive to the pest if you plant late. The application of post-emergent insecticide will also be helpful. Furadan 4F is one of the best brands to consider. However, it is critical to choose the right time for its application. Spraying it too early will cause leaching and when too late, on the other hand, it will lack effectiveness.

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