The Beneficial Nematode—The Insect Destroyer

A beneficial nematode is one that provides control of many pest insects. Steinernema and Heterorhabditis nematodes provide the best control when the right environmental conditions to keep them healthy.

These nematodes target many insects such as:

Weevils Billbugs Black vine weevil Strawberry root weevil Citrus weevils Carrot weevils Caterpillars Cutworms Army worms Sod webworms Artichoke plume moth

Clear wing moth Iris borer Flies Fungus gnats Sciarid larvae Beetles Flea beetles Mole crickets Flea (larvae) Japanese beetle grubs

The main beneficial nematodes used by gardeners are Steinernema carpocapsae and Heterorhabditis bacteriophora.

If you have these two handy to spread on your property, then many of the harmful insects will be taken care of.

There are other nematode species that specialize. They eradicate only certain types of insects.

Although there's a beneficial nematode for that pest you want out of your lawn or garden, there's currently no commercial supply of many of them.

Beneficial nematodes are safe for plants and animals (worms, birds, pets, children).

If you use organic fertilizers, there are no special precautions.

With inorganic fertilizers there are, so check the label of the fertilizer to know what's in it, and check the nematode package's label for any warnings.

Below you'll find a list of beneficial nematodes and their main dish.

Steinernema

These nematodes will sit and wait for their meal.

• Steinernema carpocapsae: probably the most important of the nematodes. Easy to reproduce and last for months in proper storage.
• Steinernema feltiae: Attacks primarily mushroom flies, fungus gnats, and tipulids. This nematode is unique in maintaining infectivity at soil temperatures below 10°C. S. feltiae offers lower stability than other steinernematids.
• Steinernema glaseri: The largest one at twice the length but eight times the volume of S. carpocapsae infective juveniles. Attacks scarabs. This species can provide control of several scarab species. The large size, however, reduces yield, making this species more expensive to produce than other species.
• Steinernema kushidai: From Japan and only known to parasitize scarab larvae. Highly promising, they too can be mass produced and commercialized.
• Steinernema riobravis: Isolated to date only from the Rio Grande Valley of Texas, possesses several features. It's effective across multiple insect orders. This nematode is effective against corn earworm and mole crickets. Works well under arid conditions and on one occasion was annually for control of citrus root weevil with impressive results.
• Steinernema scapterisci: From Uruguay and used in the USA to suppress adult mole crickets. Commercially available since 1993, this nematode is also sold as a biological insecticide.

Use S. carpocapsae on: Artichokes, for Artichoke plume moth Cranberries, for Cranberry Root weevils Cranberries, for Cranberry girdler Billbugs Armyworms Cutworms Webworms Wood borers

Use S. riobravis on: Citrus Root weevils Mole crickets Use S. feltiae on: Mushroom sciarids Fungus gnats Use S. scapterisci on: Mole crickets

Heterorhabditids

These nematodes do well against soil pests that are not as mobile because they actively search for hosts deeper in the soil profile.

• Heterorhabditis bacteriophora: Among the most important nematodes, H. bacteriophora attack insect larvae especially root weevils. Is less effective in cooler temperatures so use above 68 degrees F (20 degrees C).
• Heterorhabditis megidis: This large beneficial nematode is marketed in western Europe for control of black vine weevil and various other soil insects.

Use H. bacteriophora on:

• Berries Root weevils
• Cranberries Root weevils
• Wood borers
• Turf Scarabs
• Billbugs
• Ornamental Root Weevils

Use H. megidis on:

• Ornamental Root Weevils

When To Apply Beneficial Nematodes, and How

The most important aspect to using nematodes is timing.

• Know when the problem insect is present in or on the soil.
• Apply in early evening or early morning as high temperatures kill the nematodes. They do best in soil that is from 60-90 degrees F (15.5-32 degrees C).

The how is important, too.

• Keep them stored properly until use, and use them as soon as possible after purchase.
• They need moisture for movement in the soil so water before and after application. Apply with watering cans, sprayers or pump sprayers.
• Two applications may be necessary.

Also important is to find and use only a reputable supplier of beneficial nematodes.

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