How To Prevent Armyworms on Tomatoes

How To Get Rid Of Armyworms On Tomatoes In 2023

In the peaceful world of gardening, the last thing you want is an unexpected army of hungry caterpillars munching on your precious plants. 

These troublemakers are called armyworms, and they may seem harmless, but they can really mess up your garden. 

But don’t worry! This guide will help you understand what armyworms are, how to spot them, the damage they can cause, and, most importantly, ten simple ways to get rid of them from your tomato plants. 

Get ready to defend your garden against these pesky invaders!

What are Armyworms?

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Armyworms are hungry caterpillars that can eat a lot of plants, like tomatoes. They look greenish-brown and have stripes on their bodies. 

They start as tiny eggs in the soil, then turn into caterpillars that do the most damage by eating plants. 

After that, they become pupae and eventually grow into moths. Knowing this helps people stop them from harming plants.

How to Identify Armyworms

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To spot armyworms and stop them from harming your plants, keep an eye out for these signs:

  • Holes on Leaves – Check your plant leaves for strange, uneven holes.
  • Chewed Edges – Look for leaves with edges that seem like something has nibbled on them.
  • Little Black Pellets – If you see small black pellets near your plants, it might be armyworm droppings.
  • Nighttime Moths – Adult armyworms are moths that come out at night. You might see them around lights.

By noticing these things and paying attention to the way they look, you can quickly figure out if armyworms are causing problems in your garden.

Damage Caused by Armyworms

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Armyworms are like hungry pests that love to eat your tomato plants. They don’t stop eating and can destroy your plants. 

They munch on the leaves, making them look like skeletons. Sometimes, they can even eat up the whole baby plants. This is bad because it makes it hard for the plant to make food and it becomes weak, getting sick easily.

When there are lots of armyworms, your tomato crop can get really hurt. You might lose a lot of tomatoes. So, it’s super important to find good ways to stop them.

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Armyworms: Discovering the Basics of These Insects

Common NameArmyworms
Scientific NameVarious species
Group NameCluster
Average Life Span in the WildSeveral weeks to months
SizeVaries (depending on species)
WeightVaries (depending on species)

Armyworms Facts Table:

Main PreyPlants, Crops
Fun FactArmyworms can cause significant damage to crops and are known for their migratory behavior.
HabitatAgricultural fields, grasslands
PredatorsBirds, Insects, Spiders, and more
Average Litter SizeHundreds to thousands (depending on species)
Favorite FoodVarious Plants, especially young and tender ones

Armyworms Physical Characteristics Table:

ColorVaries (depending on species)
Skin TypeSoft body, no fur
Top SpeedVaries (depending on species)
LifespanSeveral weeks to months
Weight RangeVaries (depending on species)

10 Methods On How To Get Rid Of Armyworms On Tomatoes

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1. Handpicking

Handpicking is a labor-intensive but highly effective method for armyworm control, especially in smaller gardens. 

To employ this technique, inspect your tomato plants regularly, preferably during the early morning or late evening when armyworms are most active. Wear gloves and simply pluck the caterpillars off the leaves. 

Be thorough in your search, as missing even a few armyworms can lead to a resurgence of the infestation. Dispose of the collected caterpillars far from your garden to prevent their return. 

While it might seem tedious, handpicking can significantly reduce the population of armyworms and protect your tomato crop without resorting to chemicals.

2. Natural Predators

Harnessing the power of nature’s pest controllers is an eco-friendly way to manage armyworm infestations. 

Encourage beneficial insects and birds in your garden, as they feed on armyworms. Predatory wasps, such as parasitic wasps, are known to lay their eggs inside armyworm caterpillars, effectively killing them. 

Birds like sparrows, robins, and orioles also relish these caterpillars. Attract these helpers by providing birdhouses, bird feeders, and maintaining a diverse garden ecosystem. 

By fostering a balanced environment, you can create a natural armyworm control system that keeps pest populations in check.

3. Neem Oil

Neem oil, derived from the neem tree, is a popular organic remedy for armyworm infestations. It acts as both a deterrent and suffocation agent. 

To use neem oil, mix it with water following the manufacturer’s instructions and spray it on your tomato plants, ensuring complete coverage, especially on the undersides of leaves where armyworms often hide. 

The bitter taste and suffocating effect of neem oil disrupt armyworm feeding and respiration, driving them away from your plants. Regular applications, particularly after rain, can enhance its effectiveness. 

Neem oil is safe for beneficial insects and doesn’t harm the environment, making it an excellent choice for eco-conscious gardeners.

4. Bacillus thuringiensis (Bt)

Bacillus thuringiensis, commonly referred to as Bt, is a naturally occurring soil bacterium that produces proteins toxic to certain insects, including armyworms. 

Bt-based insecticides are available in various formulations, such as sprays, dusts, and granules. When armyworms consume plants treated with Bt, the bacterium’s toxins paralyze their digestive systems, leading to their demise. 

Bt is highly specific to caterpillars and poses minimal risk to humans, animals, and other non-target insects. 

To use Bt effectively, follow the product label instructions, apply it when armyworm infestations are in their early stages, and reapply if rain washes it off the foliage.

5. Diatomaceous Earth

Diatomaceous earth (DE) is a natural, abrasive powder composed of the fossilized remains of microscopic aquatic organisms called diatoms. 

When sprinkled around your tomato plants, DE creates a barrier that damages the soft bodies of armyworms upon contact, effectively dehydrating and killing them. It’s important to apply DE in dry conditions to maximize its effectiveness, as moisture reduces its abrasive properties. 

Wear a mask when applying DE to avoid inhaling the fine dust. Reapply after rain or heavy dew, as DE becomes less effective when wet. DE is non-toxic to humans and pets, making it a safe choice for organic gardening.

6. Row Covers

Protect your tomato plants from armyworm infestations by using row covers, which are lightweight, breathable fabric barriers that physically block the caterpillars’ access. 

Install row covers over your tomato plants, securing them to the ground to prevent armyworms from crawling underneath. 

Ensure the covers have enough slack to allow for plant growth while keeping them taut to prevent pests from reaching your tomatoes. 

Row covers are particularly useful for safeguarding young tomato seedlings and transplants. Keep an eye on your plants, and remove the covers once they start flowering to allow for pollination.

7. Crop Rotation

Crop rotation is a time-tested agricultural practice that can help prevent armyworm infestations in your tomato patch. 

Armyworms tend to return to the same area year after year if their favored plants are present. 

By changing the planting location of your tomatoes each season, you disrupt their life cycle and reduce the risk of re-infestation. 

Ideally, rotate tomatoes with non-host crops like beans or cucumbers to make the environment less hospitable for armyworms. Keep a record of your planting history to ensure you maintain a proper crop rotation schedule.

8. Companion Planting

Companion planting involves strategically planting certain herbs, flowers, or vegetables near your tomatoes to deter armyworms. 

Marigolds, for example, emit a pungent odor that repels these pests. Plant marigolds around the perimeter of your tomato patch or intersperse them among your tomato plants. 

Additionally, aromatic herbs like basil and rosemary can confuse and discourage armyworms from locating your tomatoes. 

Companion planting not only helps with pest control but can also improve overall garden health by attracting beneficial insects and promoting biodiversity.

9. Homemade Sprays

Homemade sprays can be an effective and chemical-free way to deter armyworms from your tomato plants. Garlic and chili pepper spray is a popular DIY option. 

To make it, blend several cloves of garlic and a few chili peppers with water, strain the mixture, and add a few drops of dish soap to help the solution adhere to the leaves. 

Spray this concoction on your tomato plants, ensuring good coverage. The strong odor and spiciness of the spray can repel armyworms. 

Reapply after rain or as needed to maintain its effectiveness. Homemade sprays are environmentally friendly and pose no harm to humans or pets.

10. Chemical Insecticides (Last Resort)

Chemical insecticides should be considered a last resort for armyworm control, as they may harm beneficial insects and the environment. 

If other methods have failed and the infestation is severe, consult with a local agricultural extension office or garden center for appropriate chemical recommendations. 

Follow the product label instructions meticulously, wear protective clothing, and apply the insecticide during calm, non-windy conditions to minimize drift. 

Be aware of the potential consequences and use chemical insecticides sparingly, prioritizing eco-friendly alternatives whenever possible.

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5 Effective Strategies On How To Prevent Armyworms on Tomatoes

1. Regular Inspection

The first line of defense against armyworm infestations is regular inspection of your tomato plants. 

Check the leaves, stems, and undersides of leaves for signs of armyworm activity. Look for chewed edges, irregular holes in leaves, or droppings that resemble small black pellets. 

Early detection allows for prompt action, minimizing damage and the need for aggressive control measures.

2. Healthy Soil

Maintaining healthy soil is crucial for preventing armyworm infestations. Well-nourished tomato plants are better equipped to resist pests. 

Ensure your soil is rich in organic matter and nutrients by amending it with compost or organic fertilizers. 

Healthy plants are less susceptible to damage and can recover more effectively if armyworms do make an appearance.

3. Proper Plant Spacing

Avoid overcrowding your tomato plants, as closely spaced plants can create an environment where armyworms can easily spread from one plant to another. 

Adequate spacing provides better airflow, reduces humidity, and makes it more challenging for pests to move between plants. Follow recommended plant spacing guidelines for your tomato variety to create a less favorable environment for armyworms.

4. Trap Crops

Strategically planting trap crops can divert armyworms away from your precious tomato plants. Corn is an excellent trap crop for armyworms. Plant corn at the edge of your garden or near your tomatoes. 

Armyworms are particularly attracted to corn, and by luring them away, you can protect your tomatoes from infestation. Remember to monitor and manage the trap crops, as they may become infested.

5. Early Planting

Timing is crucial when it comes to armyworm prevention. Plant your tomatoes early in the season, if possible, to avoid peak armyworm activity. 

By establishing your tomato plants before armyworm populations surge, you reduce the likelihood of encountering a severe infestation. 

Early planting also allows your tomatoes to grow and become more resilient before the pests become a significant threat. Keep a close eye on your plants as the season progresses to address any potential armyworm issues promptly.

Implementing these preventative measures can significantly reduce the risk of armyworm infestations in your tomato garden. By combining regular vigilance with proper garden practices, you can enjoy healthy tomato crops without the hassle of battling these persistent pests.


When it comes to fighting against armyworms, having the right knowledge is your best tool. 

If you understand these pests, how to spot them, and the harm they can cause, you can protect your garden and keep your tomato plants safe. 

Just remember, finding them early and taking action can save your garden from these persistent invaders. 

So, get ready, garden warriors! Let’s make sure our gardens stay free from armyworms!

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