Tomato hornworms, or Manduca quinquemaculata, are among the most destructive garden pests. These large, green caterpillars can cause a lot of damage to plants, feeding on tomato leaves and stems and pieces from the fruits.
They often go unnoticed due to their protective coloring and can be particularly devastating in midsummer, continuing to wreak havoc throughout the rest of the growing season.
Preventative steps can be taken to avoid an infestation, but if caught early enough, these creatures are relatively easy to control.
Though not addressed quickly and effectively, tomato hornworms can quickly decimate entire crops. Growers need to pay close attention to their plants and look out for signs of a potential infestation, such as large areas where feeding has occurred before they spot the actual pest.
This guide will provide all the information necessary to deal successfully with tomato hornworms so that your beloved plants can stay safe and healthy.
Understanding the Tomato Hornworm
Tomato Hornworms are the larval stage of the Manduca quinquemaculata, a five-spotted hawk moth. They are notorious for destroying plants in the nightshade family, such as eggplants, tomatoes, peppers (ranging from jalapenos to bell peppers), potatoes, and even tobacco plants.
These pests can be identified by their chewing holes on late spring leaves and the defoliation of host plants as they feed.
As an adult, the tomato hornworm becomes a powerful sphinx moth or hawk moth that derives its sustenance from nectar in various flowers. Its activity is most noticeable after sunset until right before sunrise.
An Overview of the Tomato Hornworm Life Cycle
Tomato Hornworms have a distinct life cycle that begins in late spring and can span two generations a year. During this time, adult moths emerge from the soil as dark brown pupae and mate, laying spherical green eggs on the underside of leaves.
After approximately five days, these eggs hatch into larvae that pass through five or six stages over the course of three to four weeks before burrowing back into the soil to transform into pupae.
In two to four weeks, adults develop and work their way to the surface, where they once again mate and lay eggs for the next generation of hornworms. This cycle then repeats until the next late spring, when it begins again.
Comparing Tomato Hornworms and Tobacco Hornworms
The tomato hornworm and the tobacco hornworm, Manduca sexta, are common inhabitants of gardens that host members of the Solanaceae plant family. The tomato hornworm is a 3 to a 4-inch-long green caterpillar with eight diagonal white stripes running along its sides and a black horn protruding from its back.
In contrast, the tobacco hornworm has seven white diagonal stripes on its body and a red horn instead of black. The adult form of this species is known as the tobacco hawk moth or Carolina sphinx moth. These two species may be mistaken for each other at first glance due to their similar appearance. However, they can easily be distinguished by these unique features.
Identifying the Tomato Hornworm
Tomato hornworms are an omnipresent and destructive pest to gardeners growing tomatoes, eggplants, peppers, and potatoes. They are easily identifiable due to their large size (3-5 inches long), light green bodies with white and black spots, V-shaped stripes, and long black horn that sticks out of their rear end. Though harmless, the sight of it can be frightening. However, they can easily be overlooked thanks to their ability to blend in with the foliage.
The life cycle of a tomato hornworm begins as an adult moth known as a hummingbird moth or sphinx moth, which has gray-brown mottled wings with yellow spots on the sides of its abdomen and alternating light and dark bands on its hind wings.
These moths have 4-5 inches wingspan and fly quickly while hovering like a hummingbird. The female moths lay light green eggs in batches of up to 2000 eggs over one month’s time on the undersides of leaves at night, which hatch into larvae within a week after turning white.
Once mature, these caterpillars will burrow into the soil to enter the pupae stage, which are large reddish-brown cocoons that can overwinter in the soil, thus making them a long-standing threat for gardeners during multiple growing seasons. As all stages of this insect’s life cycle are destructive in nature, one must take extra caution when dealing with them.
To find them among your vegetables or plants, you should look for black droppings (frass) on leaves and spray the foliage with water at dusk, dawn, or nighttime when they are most active, as they will thrash about when disturbed by water exposing their hiding spot.
Additionally, using a UV flashlight is an effective way to locate them as they glow under its rays while also looking for wilted hanging leaves and stems that have lost part of their leaves, as these could be nearby host sites for these pests.
Understanding The Devastation of Tomato Hornworm Infestations
Tomato hornworms can cause significant damage to gardens, particularly to tomato plants. These pests are difficult to spot due to their excellent camouflage, but telltale signs of their presence include large holes in the plant’s foliage and eaten away stems. The larvae feed primarily on leaves and are capable of defoliating an entire plant in a short amount of time. Additionally, they may chew through the fruits, leaving them vulnerable to sunscald and other environmental damage.
The adult moths lay many eggs on a single plant, causing a wave of destruction if not addressed quickly. Tomato hornworms typically start by feeding on the tops of tomato plants, leaving behind huge holes or stumps where stems used to be. Once the foliage has been stripped from the plant, these pests will also move on to devour juicy fruits.
Identifying these destructive vermin can be tricky due to the similarities between their damage and that of other leaf-munching insects. However, black droppings left behind by tomato hornworms can provide a clue that they are present. Thus, gardeners must act quickly when they suspect tomato hornworm activity to prevent further destruction in their gardens.
Strategies To Control & Prevent Tomato Hornworms
Companion Plants and Beneficial Insects
Tomato hornworms can be a major problem for gardeners, but with the introduction of certain measures, their presence can be minimized or even eliminated. One way to control tomato hornworms is through the use of beneficial insects like Trichogramma wasps.
These tiny parasites lay their eggs inside the eggs of tomato hornworms, preventing them from hatching and hampering their life cycle. To attract these wasps to your garden, you can either buy them online or introduce them through the use of companion planting with flowers such as buckwheat and sweet alyssums.
Other beneficial insects like ladybugs and lacewings can help fight against tomato hornworms by feeding on their eggs. Planting marigolds and roses can also draw these beneficial insects to your garden so they can control tomato hornworms.
With these methods, you can protect your tomatoes and other vegetables from the threat of tomato hornworms.
Handpicking
Tomato hornworms can be a nuisance to tomato gardeners, but natural methods can effectively control them. Handpicking these large green caterpillars off the plant is the most effective way to eliminate them.
It may seem intimidating, but tomato hornworms are not dangerous and can be handled without fear of being bitten or stung.
Once collected, the hornworms can either be relocated where they will become helpful pollinators for your garden, dropped into a soapy bucket of water to kill them, or even fed to chickens if you have them on your property.
Hunting down these caterpillars in the foliage can be difficult as they blend in well with their surroundings; however, spraying plants with water and shaking the leaves could help make them more visible.
An ultraviolet (UV) light may also be useful for spotting tomato hornworms since their green bodies will easily appear against its glow. Catching and eliminating tomato hornworms becomes much easier with either of these methods.
Neem Oil
Neem oil is a powerful weapon in the battle against garden pests. It’s accessible and, luckily, not difficult to apply and thus making it an indispensable companion for any gardener.
Neem oil is a powerful natural insecticide for several pests that threaten tomatoes, including whiteflies and aphids. It is also an efficient weapon against the destructive tomato hornworm. Not to mention its effectiveness in combating some types of fungal diseases.
Although using neem oil for tomato hornworms is an effective solution, it also has drawbacks. Neem oil will not harm your plants but can prevent and deter beneficial insects from entering space.
Therefore, utilizing neem oil might not be prudent if you have worked diligently to introduce helpful bugs into your garden. Therefore, you must consider all of your options before applying this method to defeat tomato hornworms.
Applying neem oil to your tomato plants creates a thin coating on the stems and leaves, preventing eggs from hatching and discouraging voracious pests such as tomato hornworms. Additionally, by smothering any bugs currently residing on the foliage, this natural remedy helps ensure their demise.
Applying neem oil sprays to your tomato plants is simple and straightforward. For an effective solution, you must combine one tbsp of neem oil and two cups of water in a spray bottle.
Remember that when spraying the leaves, focus on their undersides, as this is where most eggs are typically located – ensuring maximum protection against tomato hornworms.
Till The Soil
Tomato hornworms spend their wintertime in the soil but become moths during summer. Although these creatures are not capable of causing damage in this adult stage, they lay eggs on plants that can be vulnerable to harm from them, thereby continuing a yearly cycle of destruction. That is why tomato hornworms can become such a persistent problem for gardeners.
To break the cycle of tomato hornworms, it is necessary to plow the soil at both the start and conclusion of every gardening season. This subsumes any lingering pupae deep in the earth, thereby reducing their chances of developing into adults that spread eggs.
Incorporating tilling into your pre-season garden routine is a must for any gardener. Not only does it prevent the tomato hornworm’s life cycle from progressing, but it also eliminates other pests that have been overwintering in the soil.
During the cooler months, numerous soil-borne diseases linger and can harm your tomatoes or other plants. Fortunately, tilling the land is an effective solution that not only destroys these maladies but also loosens up the soil while destroying any weeds in its path.
Mulching
Applying mulch around your tomato plants is an uncomplicated technique to ward off annoying hornworms and keep newly born hummingbird moths from laying eggs.
In the battle against tomato hornworms, black plastic mulch is a top-notch choice from other available mulching materials. It acts as an impenetrable wall that prevents moths from reaching the soil’s surface and eventually causes them to perish beneath it.
Not only does mulching help to keep weeds away and prevent overwintering insects from taking root, but it also protects tomato plants from water splashing onto their leaves which can cause fungal diseases. Therefore, the many benefits of mulching make it an excellent choice for any garden.
Botanical Bt
You may need to act more aggressively if you have a significant tomato hornworm infestation. Fortunately, there are still ways to manage pests without using dangerous pesticides.
When faced with an outbreak of tomato hornworms, Botanical Bt (Bacillus thuringiensis) is the very best natural pesticide available.
Bt is a naturally-occurring, soil-dwelling bacteria that coats the leaves of your tomato plants in an invisible protective shield. When ingested by tomato hornworms, it causes paralysis in their digestive systems and stops them from munching on tomatoes, ultimately leading to these pesky insects’ death.
Bt provides an advantage over neem oil because it has minimal impact on beneficial pollinators such as bees.
Bt is most effective when applied to recently hatched tomato hornworms. However, it can still yield successful results on worms of any stage.
Bt kurstaki is the strain that targets tomato hornworms specifically, and it’s most effective when applied to newly hatched worms. However, even older worms can still be affected by the bacterial agent. It’s important to apply Bt regularly to maintain its effectiveness against these pests.
Row Covers
Experienced tomato farmers are more than familiar with the power of floating row covers. Not only do these tools cost a small investment, but they’re also simple to make for all the DIYers out there.
With just PVC piping and shade cloth, you can easily assemble your system that is guaranteed to help efficiently protect your tomatoes from insects or extreme temperatures.
Row covers are a must-have for tomato gardeners, providing an outstanding barrier against the notorious Tomato Hornworm. As if that weren’t enough, Row covers also deter hummingbird moths from hatching their eggs on your beloved plants.
Investing in these RowRow covers will ensure that your garden remains healthy. They will protect your plants from different types of pests and diseases and keep them secure against environmental factors such as the scorching sun or extremely cold temperatures.
Crop Rotation
In the same way, you cultivate and condition your soil, crop rotation is an important gardening practice that can rescue your tomatoes from the disastrous consequences of tomato hornworms.
Rotating where you plant tomatoes each year will reduce the likelihood of pupae overwintering in the same spot and wreaking havoc on future harvests.
Not only does crop rotation ward off the threat of tomato hornworm infestations, but it also prevents the spread of overwintering diseases and other pests. Having your soil take some time away from its regular crops each season is a major benefit.
Conclusion
Tomato hornworms may seem intimidating, but with the right natural control and prevention methods, you can protect your tomato plants from them and ensure a successful harvest.
With these techniques, you’ll be able to identify signs of infestation early on and take action before it’s too late. Don’t let tomato hornworms ruin your summer tomato harvest – start implementing these strategies now.
