Beneficial Nematodes - FAQ's

Nematode FAQsWhat Are Beneficial Nematodes and How Do They Work?
Beneficial Nematodes are microscopic, non-segmented roundworms that occur naturally in soil throughout the world. Inside the nematode's gut is the real weapon — symbiotic bacteria that when released inside an insect kill it within 24 to 48 hours. The nematodes enter the larvae via the mouth, anus, respiratory openings, or directly through the body wall of the pest. The nematodes then eject their symbiotic bacteria inside the pest's body. The bacteria multiply and cause blood poisoning of the pest, leading to death. The bacteria also convert host tissue into nutritive products, which can easily be taken up by nematodes. Inside the dead insect, the nematodes feed and multiply. As the food resources within the dead pest become scarce, the nematodes will exit the dead insect and immediately start searching for a new host.

How Do I Choose the Right Nematodes?
The table below gives an explanation of the two varieties of nematodes we sell. Choose the correct nematode by determining if your pest is MOBILE or STATIONARY. Good examples of mobile pests are Fleas, Caterpillars, and Worker Ants. Good examples of stationary pests are Grubs and queen ants/termites. Grubs remain in a rather fixed position in the soil, feeding on roots while queen ants/Termites stay in one place laying eggs. The reason you need to think about the mobility of your pest is that nematodes have different kinds of hunting strategies. Some nematodes are ambushers — they wait to attack passing pests. Some nematodes are hunters — they actively seek out pests in the soil.

See our complete Beneficial Nematode Selection Charts.

When Should They Be Applied?
Apply early in the morning or predusk when temperatures are cooler and the sun is not so bright (UV rays harm nematodes). Timing of applications during the year depend on the specific pest being controlled and their life cycle. Remember, beneficial nematodes control soil-dwelling life stages.

Fall Usage Note: As temperatures cool in the fall, pest insects move deeper underground for winter. If you have noticed grubs and your night time temperatures are too low for applying nematodes, just wait and use nematodes in early spring. Grubs and other dormant pests will not destroy anything until spring. As the grubs begin to emerge from their dormant stage you can be ready with beneficial nematodes to take care of the problem right away.

How Long Can Nematodes Be Kept Before Use?
Beneficial Nematodes should be used as soon as possible. Because they are live organisms, it is best to store them for no longer than 2 weeks in a refrigerator that is between 37° and 42° F.

Optimum Temperatures to Apply Beneficial Nematodes:
Air Temperature: Apply beneficial nematodes when night time temperatures are no lower than 40° F.
Soil Temperature: (2" below surface) No lower than 42° F and no higher than 90° F. The air temperature guide above is a good rule for estimating soil temperature.

What's the Application Rate?
It is best to make at least two applications, separated by 7-10 days in order to stagger the life cycles of the nematodes and to assure complete coverage. In cases of severe infestations, applications should be made every 7-10 days or until infestation subsides.

Package Size Quantity Treatment Area
1/2 Garden Backyard Size 5 million 1,600 sq. ft.
Garden Size 10 million 3,200 sq. ft.
Farm Size 50 million 1 Acre
Small Ranch Size 250 million 5 Acres
Large Ranch Size 500 million 10 Acres

How Are Nematodes Applied?
The solution can be applied using a watering can, Hose End Sprayer, backpack or Pump Sprayer or through irrigation or misting systems. Mix nematodes into water and gently agitate. Apply when the sun is low on the horizon as the nematodes are photophobic and do not like direct light. See our video on how to apply nematodes here.

To determine the mix rate of nematodes to water:
The mix rate of nematodes with water is highly variable due to water pressure, differences in application equipment, how fast or slow you walk while applying, how long your stride is – all of these factors play into the 'how to' of applying beneficial nematodes. The bottom line is that you need to do a small experiment first and it will be simple after that!

Here's the Test Run:

  • Place a small amount of food coloring in the hose end sprayer container that you will be using to make the application. Make it a bright color so you can see it as it dilutes in your experiment.
  • Mix this with a specific amount of water of YOUR choosing
  • Go out to the area you need to spray. Then walk and spray until the food coloring is gone. Eyeball what percentage of your area was covered – was it 10%, 25%, 50%?
  • Once you figure out how far that initial mix went you can easily do the math to determine how much of the nematode package to use with each re-load.
  • If you have nematodes left over after the first round, just re-do the process and increase the mix rate of nematodes to water.

For best results use a Hose End Sprayer that allows you to set the mix rate. Do not use a hose end sprayer that does not have the ability to spray in controlled doses.

Should The Soil Be Moist After The Nematode Application?
The soil should be moist at time of application and lightly watered immediately after application. After application, regular watering of the treated area will provide sufficient moisture. Generally speaking, water every 3-4 days if rainfall does not occur.

How Long Does It Take To See Results?
In general 3-7 days for caterpillars such as cutworms, armyworms, sod webworms. For grubs and Weevils such as Japanese Beetle, black vine weevil and billbugs feeding stops within 3 days with maximum control occurring over 2-4 weeks. Nematodes disintegrate the pests from the inside out. You will not see dead insect bodies as you would with a chemical knockdown.

How Often Should Nematodes Be Applied?
Nematodes are recommended for use whenever larvae or grubs are present. Generally, this is during the spring and fall months. Because larvae feed on plant roots, beneath the soil surface, severe damage can be done before realizing there is a problem. Look for signs of an adult insect, such as leaf-notching. If adult insects are present, their eggs will be hatching soon. Keep in mind, one application may not eradicate a population of insects that has become established over a period of years.

Will Nematodes Live Through The Winter?
In general, harsh winter weather in most parts of the country almost guarantees a significant decline in the population of the nematodes. In most cases, nematodes (just like insects) will become dormant during cold weather. Any survivors would be few in number to provide adequate insect control. If your insect pest returns the following year, another application may be necessary.

When Nematodes Are Applied To One Area Will They Move To Other Areas?
Nematodes, due to their microscopic nature have limited range of movement. Generally NemAttack™, our formulations of Steinernema will stay where you put them, but NemaSeek™ (Heterorhabditis) will continue moving through the soil until they find a pest to infect.

How are Beneficial Nematodes Shipped?
REFRIGERATE UPON ARRIVAL. Remove nematode tray(s) and sleeves from insulated shipping container or packaging and place in refrigerator until ready to use. The Beneficial Nematodes are shipped in an easily dissolved formulation that you mix with water.

Will the beneficial nematodes harm my dog?
Beneficial nematodes can be used around and will not harm mammals, aquatic life, birds, reptiles or amphibians.

Termite Control?
Apply the Triple Threat Combo to get the best control. One "farm size" (1 acre coverage) nematode package will treat 40 linear feet of foundation and repeat applications are usually necessary when controlling termites. NemaSeek (Hb) parasitizes queen termites, NemAttack (Sc) parasitizes worker/soldier termites and NemAttack (Sf) parasitizes subterranean termites.

Apply nematodes along the perimeter of the structure to be treated. Use as much water as necessary to carry the nematodes down into the soil. Beneficial Nematodes are washed into the termite tubes, tunnels, and nests, or they migrate on their own. If the nest/colony is identified, apply directly to that area. Once inside the nest, they kill the colony by killing the queens or by killing enough workers and soldiers that the queen starves. While beneficial nematodes can be applied to active galleries they should not be relied upon for control if damage is extensive.

Additional Nematode Information


ARBICO Organics Guarantees Live Beneficial Nematodes Upon Arrival of Product. Call us at 1-800-827-2847, Mon – Fri, 8AM – 5PM Arizona time and on Saturdays from 8AM – 1PM with questions. We look forward to speaking with you!

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