Manduca quinquemaculata or tomato hornworm is not a worm, but a caterpillar. The color is green and the average length is 4.5 inches. It has a horn at the end of its body, which is where the name is derived from. They may be large, but because of their color, they camouflage, and hence, making it challenging to spot their presence in their host plants. Caterpillars will also have eight white marks on each of their sides. When they fully grow into an adult, also called hawk or sphinx moths, they develop narrow wings on their front.
Tomato Hornworm’s Habitat
They are common in many household gardens where there are plants with broad leaves. Aside from the leaves, they also thrive in soft soil. As hornworms turn into adults, they prefer places where there are lights. If you have a porch light, you will see adult moths surrounding such in the evening. When they are still in the form of eggs, you can find them under the leaves of the host. They affect not only the leaves, but also the roots.
Identifying Tomato Hornworm’s Damage
This pest exclusively thrives in the plants that belong to the Solanaceae or nightshade family. They are flowering plants that are known for their economic importance. The most common hosts are tomato and tobacco. It can also affect other plants in the garden, such as potato, eggplant, and pepper. They also survive in some species of foods. When they are already adults, they also feed on the nectars of flowers.
Unsure if tomato hornworms are also infesting your plants? Below are some of the signs that you need to watch out for:
- Among others, one of the most common symptoms is the appearance of holes in the leaves. Worms have the same color as the leaves, which makes it difficult to point out their presence. Also, because of their large size and a huge appetite, it won’t take long before they devour the whole leaf. This means that they will not only cause holes, but the entire leaf can disappear.
- You also have to pay attention to the appearance of frass, a sticky substance that tomato hornworms excrete. These are black or green droppings that you will usually find on the leaves of the host plant.
- The fruits will also show visible signs of damage, especially those that are soft. Excretions from the pest can be present on the surface and there can also be holes, which is a sign that they have been chewed by tomato hornworms.
Results of Infestation
As voracious feeders, expect that the presence of tomato hornworms can result in massive damages. If you do not act as soon as they wreak havoc, they can lead to severe defoliation within just a few days. In some cases, only the veins or the skeleton of the plant will remain, which will lead to its death. The effects are most devastating amongst farmers as they will lead to significant reduction in crop yield. In most instances, the crop will no longer be marketable, resulting to profit loss. Most of their damages will start during the middle of summer.
How to Get Rid of Tomato Hornworms
Natural and Organic Solutions
If you are thinking of how to deal with the pesky tomato hornworms in a manner that is safe and effective, the following are some of the things you need to do:
- Handpicking the tomato hornworms should be the first step in your list of control measures. This is an exhausting task, especially for large plantations. This works best only for small home gardens. Also, because the color of the caterpillar is similar to that of the leaves, seeing them can be quite difficult. There is no need to worry as they do not bite and will not pose any danger. Cut the caterpillar into half and dispose in a bucket of soapy water to kill them.
- Encouraging natural predators in the garden will also be an effective solution. They will feed on the hornworms and kill them. You can plant flowers with pollen or nectar to encourage beneficial insects. You can also purchase and release them in the garden. Some of the best examples of their natural enemies include ladybugs, lacewing larvae, and parasitic wasps.
- You can also use natural spray products. These are different from the usual pesticides with toxic chemicals. Look for those that contain Bacillus thuringiensis. The latter is a bacterial disease that will kill only the caterpillar pests and not other insects. It also does not pose any harm to humans or the environment in general. It produces protein, which, in turn, will paralyze the digestive system of tomato hornworms to kill them.
- Roto-tilling the soil is another method that is promising in terms of the outcomes it can deliver. This is also an effective measure for prevention, not just elimination. These pests stay under the soil during the winter and they emerge only during the spring. With this, to control their population in the next growing season, tilling the soil is a good idea to kill them.
Chemical control is not the best way to deal with tomato hornworms. However, there are some situations wherein the problem is already too severe and you have no choice but to use strong chemicals with toxic ingredients. Permethrin and carbaryl are two of the most common chemicals in insecticides that you can spray on the host plants. Regardless of what chemical you choose, proper application is critical to ensure that it will yield the highest level of success. Follow the directions from the manufacturer. Also, when spraying chemical insecticides, make sure to coat the entire portion of the plant you are treating, focusing on the underside of the leaves.
How to Prevent Tomato Hornworms
Early detection and immediate action are necessary to prevent the large-scale infestation of tomato hornworms. With this, one of the best preventive measures is cultivation during the fall. This will kill them even before the growing season. Tillage, according to gardening experts, kills as much as 90% of the tomato hornworms. Be sure, however, to do it before the growing season. Interplanting, such as with marigolds, basil, and dill, will also help in the prevention of tomato hornworms.