Using Nematodes to Kill Fleas – Complete Guide and Recommendations

Fleas are tiny insects that can bring a widespread problem in your home. As much as fleas are small, you can actually use something that can outsmart their sneaky behavior. Here’s where using nematodes to kill fleas comes handy.

BioLogic Scanmask Sf
Beneficial Nematodes
Check Price
Bug Sales Live Hb
Beneficial Nematodes
Check Price

Beneficial nematodes are microscopic organisms widely used in the pest control industry. Various nematode species can be used to kill bugs, termites, and other insect pests.

So how can you use it? How can you guarantee its efficacy? Read on our full post to the answers.

Beneficial nematodes

Beneficial nematodes come in three different species. Each one has different behaviors and is used for specific insect pests. These are the following:

*Steinernema feltiae (Sf)

Widely referred to as Sf, this beneficial nematodes species is commonly used to control pest fly population as well as other insects like fleas, mites, and bugs. It’s also a common choice for eradicating a flea infestation.

This can come anywhere between 5 million to 100 million nematodes per pack.

* Steinernema carpocapse (Sc)

This beneficial nematode targets the larvae of soil-dwelling insect pests. Sc is also effective against fleas, German cockroach, fruit flies, codling moth, Subterranean termites, and more.

* Heterorhabditis bacteriophora (Hb)

Hb nematodes are naturally occurring organisms on the soil, but only in small amounts. For this nematode to work its magic on insect pests, it has to be applied lavishly.

Overall, it targets Japanese beetles, weevil, grubs, cucumber beetles, red imported fire ant, and more.

How does it work?

So how do beneficial nematodes take care of business? Once deployed, these organisms will hunt for the fleas and other insect pests. Technically, these nematodes are roundworms which will feed on the body of the host.

Beneficial nematodes will enter the body of the insect through the mouth, anus, or its skin. Once they gain entry, the nematodes will now feed and release gut bacteria that are poisonous for the host. The insect pest will die within 24 to 48 hours upon the entry of the nematodes.

Once the nematode is done feeding on the dead insect, it will exit and continue to look for another host. This is why nematodes work continuously in eradicating an insect pest as long as they are applied correctly and in an ideal location.

Even if nematodes are deadly for insect pests like fleas, it doesn’t harm crops, furry pets, and humans. Also, it’s very rare for beneficial nematodes to trigger allergies or irritations if handled well.

Nematodes can be used both indoors and outdoors, but the application will vary.

Do all nematodes kill fleas?

All the three nematodes we mentioned above (Sf, Sc, and Hb) are known to kill fleas. Some suppliers of beneficial nematodes will try to blend these types to cover more insect pests.

Aside from the species, you should also mind the application of beneficial nematodes. These organisms are light-sensitive and they need to stay within a moist place. Storage is also crucial to ensure that the nematodes will remain alive and active.

Are nematodes harmful to humans and pets?

Beneficial nematodes are proven to be safe for humans, kids, and pets. These organisms only feed on specific insects and therefore wouldn’t harm the beneficial insects if used outdoors.

In fact, beneficial insects were proven to be immune to the nematodes. With this, nematodes will only kill those that are considered as pests.

Aside from that, the Environmental Protection Agency (EPA) has exempted nematodes from federal registration. It’s a testament that this is safe to use, even on edible vegetation.

Also, you no longer have to keep the pets away when applying these organisms. Unlike chemical flea solutions, nematodes aren’t abrasive.

Using nematodes to kill fleas

For this part, we will teach you how to deploy the nematodes properly. This way, the organism will work at its full potential. Here are the simple steps:

What you need:

*Beneficial nematodes
*Clean water
*Spray bottle

Step 1. Purchase the right nematodes

Make sure that you purchase the right nematodes that kill fleas. If you have no clue where to get yours, we’ve reviewed two options below that you can buy now.

Take note that nematodes are sensitive to heat and light. If possible, purchase it from a provider nearest to you and can guarantee that the shipping process won’t kill the organisms.

Step 2. Mix the nematodes with water

Once you have the nematodes, mix it into the water on a bucket. Mix the amount that you’re going to apply within 30 minutes. Nematodes that are mixed in water for more than that timeframe will die and lose its flea-killing abilities.

Also, let the nematodes sit on the water for a minute or two before transferring it to the spray bottle.

PRO TIP: Mix nematodes on a dark place. If possible, deploy the organisms at night and in tap water. In addition, extreme temperatures can quickly kill the nematodes.

You can also use a watering can or hosepipe for this.

Step 3. Spray or douche it on the affected areas

After transferring the nematode water to the spray bottle, apply it right away. It’s best to add two drops of food color on the mixture, so you’ll know if you’re already running out of supply.

Also, shake the bottle in between sprays so the nematodes will be applied in equal concentrations. For outdoor spaces, you’ll need to soak the ground with the nematode-infused water.

If you’re applying this indoors, spraying it directly on the affected areas will do. For those who are thinking of spraying the nematodes directly to their pets, it’s best to ask the opinion of a veterinarian first.

Overall, nematodes aren’t used on humans or pets, so it’s better to avoid it as well.

Step 4. Re-apply as necessary

Depending on the weather on your location, you’ll need to re-apply the nematodes. For outdoor locations with very dry weather, you should re-apply the nematodes every three days for up to two weeks.

You can also spray it once a day indoors depending on the extent of the infestation.

The re-application will ensure that the nematodes will be conditioned well on the application area. It also sustains the flea protection for you and your pets.

How long before the nematodes work?

Nematodes will usually kill fleas within 24 to 48 hours once they start feeding on it.

If you’re looking forward to massive results, you’d have to wait for two weeks with regular application. Even if the nematodes come in millions, they still need time to locate the fleas and make a dent on its population.

If the nematodes didn’t seem to show results after the said timeline, you should tap the help of a flea expert. You might be applying the nematodes wrong or that the organisms are already inactive or dead before the application.

Once the fleas are eradicated or if the nematodes can’t find a new host, it will die. This prevents the organisms from being the next pest. Also, the nematodes will decompose, leaving no trace behind after the infestation.

Storing nematodes

Take note that the efficiency of the nematodes relies on how you store it. Since these are live organisms, you should only shelf nematodes for a short period. Furthermore, keeping them stored for a long time will result in their death.

Also, you have to understand that nematodes need food in order to survive. If you want to stretch the nematodes’ lifespan, it’s best to store them in the fridge. Take note: the fridge, not the freezer.

It’s best to cover the nematode container with aluminum foil to protect them against the light. Again, nematodes hate the light and they will die if exposed to it for long.

Under this condition, the nematodes can live for up to 14 days. Nevertheless, you should factor in the length of storage and delivery of the nematodes even before you put it inside the fridge.

It’s best to use nematodes as soon as possible. If you need more supply, just re-purchase new nematodes.

Additional tips

To make sure that you’ll get the right nematodes and it will work against the fleas, make sure that you keep the following points in mind:

-Nematodes can’t function well in freezing temperatures. If you’re facing a flea infestation during winter, nematodes aren’t the best option. These organisms can’t work well if exposed to extreme temperatures. Aside from that, fleas become dormant during the winter season, making the nematode treatment less efficient.

-A fishy smell on the nematodes is a bad sign. If you opened the packet or container and you smell a fishy scent, the nematodes may be already dead. The fishy smell is the odor of their decomposition. There’s no point in using such nematodes.

-Always purchase from a reliable seller. If possible, purchase the nematodes from a seller that hasn’t stored them for too long. This way, you can still keep the nematodes for a few more days.

-Apply the nematodes right away. The moment that you open the container and mixed the nematode with water, you have to apply it fast. This way, the nematodes won’t die and starve.

Where to get beneficial nematodes?

You can purchase beneficial nematodes on most gardening and home supplies stores. Just make sure that the seller is keeping the nematode supply fresh. If the nematodes have been in the store for more than two weeks, it’s likely to be dead or inactive.

 If any of these stores aren’t available in your locality, you can opt for our two options below. These are tried and tested by many gardeners, homeowners, and even pest control experts.

Top 2 Beneficial Nematode Options

OUR TOP PICK: BioLogic Scanmask Sf Beneficial Nematodes

Product Name: BioLogic Scanmask Sf Beneficial Nematodes

Product Description: The BioLogic ScanMask has the Steinernema feltiae (Sf) nematode that can kill more than 230 insect pests. It’s grown in the U.S. and will be shipped inside an insulated and iced box to ensure that the nematodes will stay alive. The 10 million nematode packet can treat up to 400 square feet. It’s also compatible with a hose-end sprayer, watering can, pump sprayer, and Nema-Jet sprayer.

Offer price: $$$

Availability: InStock

  • Killing Effect
  • Lifespan
  • Application


Aside from the Sf nematodes, the BioLogic ScanMask also comes with inactive ingredients like Diatomaceous earth and Potassium sorbate.

The best thing about BioLogic is they only ship from Monday to Wednesday to prevent the nematodes from being stuck during weekends.

Overall, this nematode product can kill fleas, fungus gnats, white grubs, armyworms, weevils, root knots, and more. This is compatible with beneficial insects like ladybugs, earthworms, and more.


✔️Will be delivered in an insulated and temperature-controlled box

✔️Shipped from Monday to Wednesday to prevent being stuck

✔️Guaranteed fresh and alive nematodes


❌If you order the Garden Pack, the two packets will arrive in separate boxes


Bug Sales Live Hb Beneficial Nematodes

using nematodes to kill fleas

If you’re treating a larger area, you should consider the Bug Sales Live Hb Beneficial Nematodes. The 50 million nematode packet can treat up to 1.5 acres and kill about 200 insect pests.

Hb can kill termites, weevils, adult fleas, pill worms, cucumber beetles, cutworms, and other invasive insects that damage your garden and pester your home.

The manufacturer recommends that you release the nematodes on the same day that you receive it. If this isn’t possible, you should store it in the fridge for a maximum of one week. You can also stretch it to two weeks, but the nematodes may start to die during this period.

For those who need to treat a larger yard, the Bug Sales Live Nematodes are available for up to 500 million nematode versions.

✔️One packet can treat up to 1.5 acres
✔️Available for up to 500 million nematode concentrations
✔️Kills up to 200 insect pest
❌It may not be delivered in an environment-controlled box

Final words

Using nematodes to kill fleas is an excellent alternative to chemical pesticides. It’s safe, effective, and affordable. Just make sure that you apply it correctly for the nematodes to remain alive and active.

What do you think of our guide? Have you used nematodes before? Let us know below!