How to Get Rid of Armyworms: Everything You Need to Know

If you are proud of how green and lush your lawn is, then watch out for armyworms. These caterpillars invade every healthy lawn they come across. Their invasion begins in early summer and can continue into autumn.

So, knowing how to get rid of armyworms can save your lawn from certain doom.

Fortunately, getting rid of armyworms is not that hard. All you need is a sound strategy and you are good to go.

Disclosure: This post may contain affiliate links. As an Amazon Associate, we earn from qualifying purchases if you shop through the links on YardThyme. For more information, read full disclosure here.

Armyworms 101: What Are They and How to Identify Them?

Armyworm eating plant

Armyworms are caterpillars of the moth Spodoptera Mauritia. These caterpillars are called armyworms because they march through your lawns in large numbers just like an army.

The moth Spodoptera Mauritia begins laying eggs in early summer and continues to lay a whooping 500 eggs every night.

And so, over the course of a typical summer month, the moth can lay upwards of 15000 eggs. Thus, effectively creating an army of larvae that would emerge as caterpillars 5 to 10 days later.

Once the larvae have emerged, they will hide during the day and sleep during the night. This cycle of hiding and feeding continues for 10 days. After this period, the caterpillars turn into moths and fly away, leaving your lawn a wasteland.

All of this might sound a bit scary and you might think that your lawn doesn’t stand a chance against these insects. But if you can identify these insects early on, you can prevent a lot of damage.

How can you tell if you have armyworms?

Armyworms are not visible during the day. They hide in the thatch and beneath the sand when the sun is out. When the night falls, they come out to feed. Therefore, your best bet to see whether your lawn has armyworms or not is to catch them in the act.

For this, you’ll need to grab your torch and go on a hunt at nighttime. If your lawn has armyworms, you’ll find them feeding on the underside of leaves. They are 1 ½ to 2 inches in length and have stripes over their bodies. The stripes can be yellow for Fall Armyworms and light for Beet Armyworms.

Another way to identify an armyworm infestation is to observe the extent of the damage. If a large portion of your lawn’s grass is gone in a few days, chances are that the armyworms are your culprits.

And yet another way to determine the culprit is to draw them out. We know that armyworms hide beneath the sand during the day. So to flush them out, mix water with liquid soap, and pour this liquid over the patch of grass. If there are larvae underneath the sand, they will come up to the surface in about 10 minutes.

Now that I’ve explained what these insects are and how to identify them, it is time to discuss how to kill them.

How to Get Rid of Armyworms

Getting rid of armyworms is super easy if you follow the right procedures. Generally, there are two ways to get rid of armyworms:

  1. Use insecticides
  2. Use organic methods

Both methods have their advantages and drawbacks.

Here’s an amazing video on how to get rid of armyworms:

How to Control Armyworms Using Insecticides/Pesticides

Almost all of us are aware that the easiest way to deal with an insect infestation is to use chemical insecticides to get rid of them. While this is true, using insecticides should only be the last resort. Insecticides and pesticides have severe disadvantages that far outweigh the advantages.

That said, insecticides are quite effective if you use them in the correct way.

First up, before using insecticides make sure that you cover yourself with the right protective gear while paying special attention to your face and hands (here are some good garden glove options). Cover them up as best as you can to minimize your risk of exposure to these harmful chemicals.

Once you have covered yourself, read the product label, and follow the directions. More importantly, always mix the pesticides according to the manufacturer’s recommendation. Never mix too much to use later. Only prepare as much as you need on the occasion.

After preparing the liquid, pick a suitable time to use it. Begin applying the pesticide so that you finish just before sunset. Once you’re done applying the pesticide, water your lawn slightly so that the chemical spreads throughout the plants.

Finally, depending upon the result you may need to repeat the process a few more times.

How to Get Rid of Armyworms Organically

Getting rid of armyworms organically requires more time than using pesticides. But it is a far better option for a variety of reasons:

The first organic method that you can use is Beneficial Nematodes. Nematodes occur naturally in dark and moist places. They are microscopic parasites that are invisible to the naked eye. Once you release them in the soil, they track down the larvae, in our case armyworms, and kill them.

The main quality of these parasitic organisms is that they are harmless to humans, pets, and plants. So, you can use them and not have to worry about any side effects.

Next up, you can also set up Pheromone Traps. Pheromone traps should only be used at the start of moth season i.e. early summer. These traps attract moths using sex pheromones. As a result, the moths get trapped and can’t lay any eggs.

Even so, the effect of pheromone traps is negligible compared to using insecticides especially if the timing is not right.

Finally, the best way to keep armyworms at bay is to encourage their natural predators. For instance, ladybugs may look cute to us, but they are a horror to armyworms. Similarly, bugs like minute pirate bugs also feed on larvae such as armyworms.

Encourage these natural armyworm predators either by refraining from using pesticides or by releasing them in your yard.

And while we are discussing armyworm predators, let us not forget about birds. Birds eat moths like there is no tomorrow. They also love to consume larvae.

Therefore, attract birds by planting trees and plants they are attracted to and removing trees they don’t like. Here is our recommendation for the best stump killers for when you need to remove some trees.

This way the birds will come for the plants but stay for the moths. It’s a win-win.

I mean, who doesn’t love birds chirping in their garden?

FAQs

Corn leaf damaged by fall armyworm

Will bleach kill armyworms?

Yes, bleach can kill armyworms. But don’t use it for other insects such as ground-nesting bees (here is the proper way how to get rid of ground-nesting bees).

But before using bleach to get rid of armyworms, make sure to take proper precautions. Cover your face and use gloves.

Once you’re fully covered properly, pour bleach in a spray bottle, and spray it on the grass, the trees, and the soil.

Make sure you don’t overdo with the bleach. Using too much bleach can be harmful to the plants in your garden.

So, for people asking ‘how to get rid of armyworms in the trees’, this is how you do it.

Does Dawn Dish Soap kill armyworms?

Dawn Dish Soap can be quite effective in killing armyworms if used properly. However, they can also be quite harmful if proper care is not taken.

The proper way to use Dawn Dish Soap is to dilute it with water. Use 3 tablespoons of Dawn Dish Soap and vegetable oil and mix it in 1 gallon of water. After that fill a spray bottle with the solution.

Remember to spray both the underside and the top of the leaves. Spray on every surface of the plants and grass.

Once done, you won’t have to ask, ‘how to get rid of armyworms in the grass’ anymore.

However, remember to use Dawn Dish Soap that doesn’t have any bleach in it. Dish Soaps with bleach are harmful to plants as well as beneficial insects.

Will Diatomaceous Earth kill armyworms?

Diatomaceous Earth is quite effective against pests, including armyworms. It’s basically the skeletal remains of fossilized prehistoric creatures called Diatoms. After grinding these remains, we end up with Diatomaceous Earth.

Upon spreading Diatomaceous Earth on a lawn, the ground-up remains act as a surface of tiny razor blades. When larvae pass through this field of razor blades, their respiratory organs get shredded. As a result, they can’t breathe, and they die.

But no matter how razor-sharp the Diatomaceous Earth is, it won’t stop bigger animals from digging holes in your yard. Here’s how to stop animals from digging up your yard.

Will grass grow back after armyworms?

Oftentimes, after an armyworm attack, the damaged grass will grow back. But there have been cases where the grass won’t grow back and will need to be re-sodded and overseeded.

So, to make sure that the grass in your lawn grows back after the attack, act as early as possible. Your swift response will ensure that the armyworms don’t eat the grass to the ground, leaving you with nothing. It also eliminates the risk of any long-term damage to the grass.

Will a weed killer also kill armyworms?

Normally, No. A weed killer will not kill armyworms. The way a weed killer works is quite different from how insecticides work.

But here’s why you should be using weed killers if you are not already:

Not only do weeds destroy plants, but they also look horrible.

If you don’t want this to happen to your garden, check out our many reviews of various weed killers for different purposes, e.g.:

Summary

Getting rid of armyworms from your lawn may seem impossible at first, but with some knowledge about these insects and their lifecycle, and a good strategy it can be done.

Just make sure that you are keeping an eye out for the larvae. Additionally, using the right insect deterrent, be it an insecticide or a homemade pesticide, can go a long way.