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Nematode Application Instructions

Nematodes are near microscopic, non-segmented, multicellular “roundworms", which occur naturally in soils all over the world. Some are bad and harm plants (root knot nematodes) or us (pinworms), and some are good and eat bad insects. (Note that “good” and “bad” are categories people made up. They don’t exist in Nature. These predatory nematodes will infest any host it can, good or bad). In balanced “healthy” soils, usually no one population of anything will get too large for too long. There is always something eating something else to keep populations in balance. There are nematodes that eat other nematodes. Some fungi trap and eat them. Earthworms live on soil microorganisms and organics they digest from the mud they eat, including nematodes. So you need to add more good beneficial nematodes to control bad insects when they get out of hand. Notice the word “control”. There are very few if any organic or even chemical treatments that give total eradication for most problems.

The predatory nematodes we recommend are Steinernema feltiae from BioLogic that they call “SCANMASK” (https://biologicco.com/). They live in the top 3 inches of the soil. Different nematodes live deeper and are called “Cruisers" as they move around looking for slow prey. Others live on the soil surface and stand on their tails waiting to “Ambush” quicker prey. S feltiae does a little of both. They may not prey on surface dwelling insects or deeper grubs as well as the others, but they are poised to prey on many of the insects that have a life stage anywhere in the soil, which makes them popular. Also surface nematodes don’t do well in our heat, and the deeper living nematodes do better in sandy soil. The predatory nematodes smell byproducts of slow moving or stationary larvae’s breathing or feeding. Then they wiggle in through the mouth, rear end, breathing pores, or just thin or damaged parts. Only one nematode is needed to kill. The nematodes have a symbiotic bacterium they keep in a pouch in their tummies they squirt out, one end or the other I guess, into the host larvae. The bacteria will digest the host around the nematodes. The nematodes then suck up the innards along with the multiplying bacteria for food. The bacteria also produces anti-microbial compounds that protect the bacteria and nematodes from other invading bacteria, fungi, ants, and such. While inside the host, they mature, look for a cute nematode, date, mate, and make babies. Several generations of nematodes may live in the host until it’s all sucked up and the babies break out and look for other prey larvae to eat. The babies are the only infective, free ranging form of the nematode. They can kill in a few days.


It’s said there are over 230 pests susceptible to S.feltiaeis. Many insect species with a soil living part of their life cycle of eggs, larvae, or pupae are at risk. Good or harmless insects are also included. Armyworms, Ant & Termite eggs, larva, or adults, Beetle Grubs good & bad, Borers, Chiggers, Mole crickets, Cucumber Beetles, Cutworms, Flea Beetles, Flea Larvae, Fly Larvae like Black Fly, Fruit Fly, Saw Fly, including Crane Flies, those long legged stupid giant mosquito-looking things that are attracted by porch lights in the spring, Fungus Gnat Larvae indoors or out, Billbug, Moth Larvae, Root Maggots, Root Worms, Ticks, Root Weevils, Sod Webworms, etc.

Tree borers can be treated by squirting a solution of nematodes into the entry hole with a needless syringe you can get at the drug store. Use a flexible tube on the end from a good hardware store to get the solution deeper into the hole. Close up the opening with mud or clay. Biologic recommends 80 ml‘s or cc’s of 1gallon bucket mix per hole.

Adult insects including those without a life stage in the soil like butterflies and their caterpillars can be infected if sprayed with nematodes.

Fire ants can be treated by strongly pouring a quart of the bucket mix (see below) of nematodes down the center hole of the mound.

Steinernema feltiae, have been shown to reduce the population of root-knot nematodes by preying on their eggs. It is important to treat plants at planting, as once the knots have developed, nematodes do not have a significant effect. If the plants you plant already have  root knot nematodes, beneficial nematodes will not help those plants but can help control the root knot nematodes you have introduced into your garden. (www.ncbi.nlm.nih.gov/pmc/articles/PMC2586509/).

Adult pest we would like to be victimized, like grasshoppers, ants, and termites, may not be preyed on in large numbers. Soil dwelling and social insects have protective measures against many harmful soil microbes they live with. Just being able to clean themselves, moving quickly, or living beyond reach, may be enough. The soil level nests of ants, and the egg and larva chambers would be vulnerable to nematodes though. Grasshoppers incase their egg pods in a hard cement substance that protects them from many ills. The adult grasshoppers can succumb to ingesting hairworm nematode eggs, but these nematodes grow 2 to 8 inches long and are not sold. Any good pest control program doesn’t count on just one method. So don’t stop baiting, or using other treatments for ants and termites, garden pests, etc. Maintaining a health yard goes along way too.


Nematodes need to be protected from heat, freezing, UV sun light, and from drying out.

Biologic states you can use their nematodes in very hot dry summers, but keeping the soil constantly moist is critical and expensive and maybe not allowed in drought years, but you may only need to do this for a few weeks to achieve the results you want. They say “…there are many pests that are well controlled with summer nematode applications such as fleas, sod webworms, flea beetles and fire ants.” https://biologicco.com/blog/tips-for-using-beneficial-nematodes-in-the-summer/.

Steinernema feltiae need moist soil at temperatures from 50°F to 85°F. Once in the soil, they can survive air temperatures below minus 20°F. Prolong heat or cold weather can affect the soil deep enough to kill them though.

They are reported to live in the top 3 inches of the soil. That may be their niche, but that can be expanded if their environmental needs are met. They are not anaerobic organisms, so they need oxygen to breath. How deep in the soil they can go to avoid temperature extremes depends on how porous your soil is, whether it is clay or sandy loam, if it’s been aerated, how much organic matter it contains, and where their food lives too.

While they need moist conditions, they are not aquatic. Flooding of the ground can drown them, and is used to do so on farms if water is plentiful. If there are cracks in your clay soil, it will be too dry for them to live. Good soil drainage, and proper lawn irrigation are therefore important.

While you can apply anytime you can keep the ground habitable for them, the prime seasons will be spring and fall. This may be when many pests are available in the soil also. A lot of grubs hibernate deeper in warmer soil during the winter than these nematodes live, and many grubs pupate into adult during the spring, and are only available to nematodes in the fall.

Along with the weather, if they eat most of their prey, or the prey matures and becomes unavailable, or they are eaten by predators, an elevated population to effectively treat a pest outbreak may drop within a month or two. You may have to reapply within this time if you are not getting the results you want. Insect pests with different life cycles may require you to apply in the spring and the fall both. With good friable, aerated soil and irrigation, you may be able to extend their effective life through the whole year though.

Steinernema feltiae is special in that it is active down to 50°F. Others are not. Take advantage of this and apply them when the soil temperature reaches 50°F about 4 inches down in the spring. Use a soil thermometer. Many insects hatch as the soil temperature reaches the 50’s in the spring. This is about the middle of February in the Dallas/Ft. Worth area.

Biologic states you can use their nematodes in very hot dry summers, but keeping the soil constantly moist is critical and expensive and maybe not allowed in drought years, but you may only need to do this for a few weeks to achieve the results you want. They say “…there are many pests that are well controlled with summer nematode applications such as fleas, sod webworms, flea beetles and fire ants.” https://biologicco.com/blog/tips-for-using-beneficial-nematodes-in-the-summer/.


Biologic sells their nematodes in either a spray-able form or in a granular spreadable form. They are shipped in insulated containers with cold packs. They ship out before weekends and holidays to avoid sitting in warehouses somewhere.

Biologic sells the “Scanmask Spray” in 10M, 25M, 50M, and a 100M sizes. This spray-able form comes in a packet with just the nematode and probably moth eggs or whatever they are bred in. This has a shelf life of 1 month refrigerated.

The “Scanmask Topdressing” granular form comes in 10M or 25M size containers. These nematodes come in a container with a packing material like vermiculite to hold moisture. This has a shelf life of a year or so refrigerated for the 10 million unit container to 6 months for the 25 million unit container. The granular form is intended for crumbling on the soil prior to watering in, around trees, in seed rows, or transplant holes, avoiding having to use spray equipment. With the extended shelf life, you may be inclined to use some now and keep some for later. If the container has been opened, the expiration date on the box will not be effective. I would use them within a month after opening. Biologic has also told me that you don’t know the distribution of the nematodes in the container without mixing it well and recommend using the whole container at one time.

Refrigerate until use. They are dormant until warmed up. Do not freeze. This will kill them. Stored in a refrigerator at 38F (4C). There should be an expiration date on the container. They will have full potency until then if not opened.

To test for viability and being near microscopic, means you can possibly see them wiggling around in a drop of water over a black background using a strong magnifying glass of 10x or better. An eye loupe may be cheaper and stronger. Dead nematodes may have straight profile. Live one usually are curved. Some don’t move at rest and need to be poked with a needle to show they are alive.


1.  Measure area to be treated to be sure you don’t over or under apply the nematodes.
2.  Water your yard first if it’s ry, with a half inch of water. They need a moist environment.
3.  Apply during the evening when the sun is going down, as ultraviolet light can kill them.
4.  Wash the nematodes into the soil after applying, with another half inch of water.


The “Scanmask Spray” comes without any packing material for only spraying. Order this form for immediate treatment. It only has a shelf life of 1 month so it isn’t something retailers keep in stock. Biologic’s instructions: https://biologicco.com/wp-content/uploads/2016/06/Sprayable-Directions.pdf.

The “Scanmask Topdressing” granular form needs to be moisten with water and mixed well with a damp bulky material like compost, potting soil, vermiculite, or sand to make hand spreading easier. Biologic’s instructions: https://biologicco.com/wp-content/uploads/2016/08/Lawn-and-Garden-Scanmask-Directions.pdf and https://biologicco.com/wp-content/uploads/2016/08/25-Million-Horticultural-Scanmask-Directions.pdf.

The “Scanmask Topdressing” granular form can be sprayed if you like the convenience of a long shelf life and having it on hand when needed. Biologic’s instructions are on the box. The following instructions are our recommendations.  Our coverage is greater than the manufacturer’s recommendations in their instructions, but we have achieved good results for most problems we treat for, at a lower cost:

Mix the container, in a separate bowl if needed, as the nematodes are not evenly distributed, or use the entire content at one time.

For the 10 Million nematode (AU;active units) Granular Pint container:

·   This will treat 1,500 square feet of lawn &/or planting beds.

·   Dump entire contents of nematodes into 1 or 2 gallons of cool distilled water in a clean bucket. Soak for 15-30 minutes, stirring occasionally.

For the 25 Million nematode (AU; active units) Granular Pint container:

·   This will treat 3,000 square feet of lawn &/or planting beds.

·   Dump entire contents of nematodes into 3 or 4 gallons of cool distilled water in a clean 5 gallon bucket. Soak for 15-30 minutes, stirring occasionally.

Best to not use the mop bucket in case there is disinfectant residue. Get a new bucket from the hardware store. You can’t have too many buckets anyway.

Don’t soak over 30 minutes. Nematodes are not aquatic. They will drown within 2 hours. This means you need to apply the mixture on the yard within these 2 hours.

We recommend distilled water (under a dollar at the grocery store) or rainwater to avoid potential affects of ozone, chlorine or chloramines disinfectants in the treated tap water. This isn’t mentioned in manufactures’ web sites, but for paranoia’s sake, as they are soaking in it, it doesn’t hurt.


However you apply the mixture, make a dry run through the treatment area to know how much to spray, squirt, or dribble on the ground to cover the area with the amount of mixture you are going to use.

The granular stuff in the jar that preserves the nematodes, will clog hose-end or pump sprayers, so must be strained out if used in these applicators. Otherwise the pressures of a pump sprayer will not harm nematodes, but remove mesh strainers if used in the sprayer. You can use paint strainers, cheesecloth, or old tee shirts to strain the mixture. There is still a lot of nematodes in the granular stuff you strained out, so don’t throw it out. Use it as mulch in vegetable or flowerbeds, in transplant holes, in seed furrows, on ant mounds, around special plants. Water it into the soil.

Due to the granular preservative, the preferred application method we recommend for homeowners, is to pour the bucket mixture into a watering can with holes in the rosette big enough to let the granular stuff pass through, or remove the rosette. If you don’t have a watering can, sprinkle out of the bucket with a serving spoon with holes in it, a can with holes punched in the bottom, or something similar.

The more even the application the better and quicker the results since microscopic worms can’t move far very fast. They probably move around more by being washed around by watering and hitching rides on insects.

Keep agitating the container to keep the nematodes stirred up.

Apply within 2 hours of mixing in water, as they will start to drown.

Neem products (pure neem oil, neem oil extracts, or dry neem meal) have nematicidal activity (will kill them). I have also read that Seaweed or Kelp extract has nematicidal activity. It appears that seaweed is detrimental to nematodes when directly treated. Applied to greenhouse plants, seaweed extracts reduced nematode infestation of tomato plants and citrus species, but no effect was found on these latter plants in the field. The bad nematodes were the ones studied with neem and seaweed, and not the good ones. To be safe, don’t apply either for a few weeks or so before or after applying our nematodes.


Vertebrates, humans, dogs, birds, etc., are completely resistant to beneficial nematodes and unharmed. Earthworms and helpful insects like bees, ladybugs, and lacewings are also resistant. Plants are completely resistant; there is no phytotoxicity. These nematodes are exempt from the EPA registration required for chemical pesticides.

As with any non-food grade substance, you don’t reuse the containers (you can just throw these away), don’t eat it, don’t let kids or pets play with it, don’t spray it on yourself or others (no water fights), and as with anything sprayed or dusted, organic or not, wear splash protective goggles and a mask suitable for the material used (cheap throw away face mask is ok here).

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