Nematodes for Flea Control – How Effective Are They? 

Updated on by Jared Belson | Please note that there may be affiliate links on this page.

Fleas on your pet or in your home are a big problem! No matter how thoroughly you treat your dog and your home, you could still have a huge source of fleas nearby- right in your very own backyard.

In order to effectively treat fleas, you need to treat your pet, your home, and your backyard. Or the flea problem will continue.

Are nematodes an effective way to kill the fleas in your yard? Find out if you can use nematodes to make your backyard free of fleas for your pet and your family!

What Are Nematodes?

Nematodes are microscopic, non-segmented roundworms. That’s right. They’re a parasite. They live naturally in soil around the world.

The nematodes we want to examine are also known as beneficial nematodes.

Nematode Characteristics

You won’t be able to see nematodes, because they are extremely small. Since they are non-segmented roundworms, their bodies are smooth. Their particular type of gut bacteria kills pests like fleas.

Beneficial Nematodes

The scientific name for beneficial nematodes is Steinernema carpocapsae. They’re considered beneficial because they kill pests, and don’t harm people or other animals. There are other varieties of nematodes (such as root-knot nematodes) that are harmful to plant life.

How Do Nematodes Combat Fleas?

As parasites, Nematodes require a host to stay alive. They actively hunt flea larvae and pupae in the soil by tasting the soil for heat. Once they’ve found a host, they create an opening in the wall of the insect’s skin and enter their body.

The Nematodes produce bacteria while inside their host that will enter the bloodstream of the flea larvae or pupae. Nematodes also reproduce inside the body of their host. This will eventually kill the host insect.

How Effective are Nematodes for Flea Control?

According to the Journal of Nematology, Entomopathogenic nematodes or beneficial nematodes are up to 90% effective to kill common pests, like fleas.

They are particularly effective when applied on top of normal soil in warm weather.  In other words, with correct application, nematodes could be extremely effective!

In addition, beneficial nematodes are inexpensive, easily accessible, and easy to apply quickly.

Are Nematodes Harmful?

You may be concerned about trading one parasite for another! It does seem a little counterproductive. Once they’ve gone through all their food sources, the nematodes will die. You don’t need to worry about a yard full of microscopic worms!


Yes, nematodes are a part of the roundworm family. However, they are only interested in pests as hosts and are not attracted to humans.

According to the United States Environmental Protection Agency (EPA)  Volume 47, Fed. Reg. 23928, beneficial nematodes are classified as “macro-organisms”. They are considered safe to use, and free from restrictions and regulations.


Beneficial nematodes are not interested in your pets as hosts. Unlike other parasites that can harm pets, nematodes are considered completely safe for use around pets.

Unlike most chemical pest treatments, you do not need to keep your pet out of your yard after the application of beneficial nematodes.

If chemicals and pesticides are a concern to you as a pet owner, I would highly recommend the use of nematodes, instead.

Helpful Insects

According to Albrecht M Koppenhofer, a professor of entomology, beneficial insects such as ladybugs seem to be immune to nematodes.

Nematodes also don’t seem to be attracted to other outdoor animals, such as birds, squirrels, reptiles, amphibians, or rabbits.

What Else Do Nematodes Eat?

Beneficial nematodes eat a variety of pests other than fleas, including:

Check the packaging label on the nematodes to get a full list of pests that can be eliminated by nematodes.

How Many Nematodes Will I Need?

Always refer to the package instructions, as different distributors have different recommendations. Most pest control specialists agree that 5 million nematodes should treat up to 1,000 square feet of lawn space.

How Long Does it Take for Nematodes to Work?

Nematodes are quick workers! Once you release beneficial nematodes into your yard, they will immediately begin searching for hosts. Once they find a host, the host will be dead within 24-48 hours. You should be able to see full results in about two weeks.

How Do I Use Nematodes for Flea Control?

Purchasing Nematodes

Nematodes are available for purchase through Amazon, and other online pest control specialists. Look at the shipping methods to ensure your nematodes arrive alive! They should be packaged in a temperature-controlled container with ice packs.

If you purchase your nematodes locally, find out where they came from, and when they were shipped. Check to see how the nematodes are stored. They should be stored in a refrigerated area.

Storing Nematodes

Nematodes can be a little particular about temperature. If they get too warm or too cold, they’ll die. Once you receive your nematodes, store them in the refrigerator.

Do not place nematodes in the freezer! They can be kept alive in the refrigerator for 1-2 weeks, but I recommend applying them to your lawn as soon as possible after they arrive.

If you open the package of nematodes, and there is a fishy odor, the nematodes are dead. Nematodes do not have an odor, normally. The fishy scent is an indication of decay. Contact the seller to get them replaced.

Applying Nematodes

  • Apply the nematodes during the early morning, or in the evening when the temperatures are cooler, and there isn’t a direct sun. Nematodes do not fare well in heat and sun. Don’t apply nematodes during the winter. Nematodes don’t like to be too cold, either, so wait until late spring or early summer for application.
  • Lightly water your yard. The nematodes will be able to burrow easily into moist soil. If you live in an extremely dry climate, water your yard daily for several days before nematode application.
  • Attach a hose end sprayer to your hose, and place the nematodes and water in the sprayer compartment. Check your package instructions to find out how much water to add.
  • Spray the entire desired area with the nematode and water mixture. Check the package for application suggestions.

Do I Need to Reapply Nematodes?

One treatment of beneficial nematodes should resolve a flea problem. If the fleas return or you need peace of mind, nematodes can be reapplied every 4 months or so.

What Else Is Needed for Flea Control?

In Your Home

For a comprehensive guide to eradicating fleas from your home, check out – How to Get Rid of Fleas in Carpet Effectively & Fast on our blog. There are a lot of options, including:

For continued flea treatment, this spray is a natural treatment that can be used in your home without a risk to your pets or family.

On Your Pet

Don’t forget about your itchy pet! Wash your pet thoroughly with a shampoo to treat fleas, like this one. Follow the instructions on the bottle, and repeat the application as needed. If the flea problem persists, you may want to consult your veterinarian.

Once your pet is free of fleas, keep them that way with a flea and tick treatment, like this one (for dogs) or this one (for cats).

Final Thoughts

Nematodes are an effective, natural method of flea control! I would especially recommend them to pet owners who are concerned about pesticide use.

Nematodes can be a little tricky to store, so make sure you purchase them from a reputable seller. Don’t forget to treat your pet and your home for fleas, as well. You should be free from pesky fleas within a few weeks!

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