Beneficial nematodes are microscopic worm-like
organisms found naturally in soil. There are many
species--good, bad and in-between. Good
nematodes kill pests in soil. They work best when
soil stays moist, killing in about 48 hours by
releasing unique bacteria inside pest larva, hence
they are called infective parasitic nematodes.
Several species are available commercially in
various size packages and formulations and will
attack a broad host range. The following
descriptions indicate which nematode species is
best for different systems and pests.

Steinernema feltiae (also Nemasys) are used in
media at 50º F to 86º F or as a foliar against:
• fungus gnat, shore fly, mushroom gnats, fruit
fly, Western flower thrips, leafminer
• biocontrol inhibition of some plant parasitic
nematodes, particularly root-knot nematodes
• house flies need 5-10 million nematodes per
25 sq. ft. of manure pile.
For high levels of fungus gnats, Steinernema move
through rockwool, peat, sawdust or soil growing
media without difficulty. They will not reproduce or
stay in the growing media and must be reapplied if
reinfestation occurs. Follow these steps:
• Apply nematodes when yellow sticky traps
average over 50-75 fungus gnat adults/trap,
weekly, or while fungus gnat populations
appear to be increasing.
• If root diseases are a problem in the crop,
apply nematodes sooner to reduce the risk of
disease transmission by fungus gnat larvae.
• Three applications 7-10 days apart are usually
required. Follow product label for rates.
• Calculate based on actual growing area (i.e.,
containers or beds) not greenhouse area.

Quantity guidelines
Beneficial nematodes are used at around 1 million per 60 ft2 and 1 billion
per acre, but product labels vary. Release every
three to six weeks until infestation subsides. The
warmer and more regular the watering system, the
lower the required rate. With lower rates, control
declines. For example, using H. bacteriophora
against Japanese beetle grubs, after three weeks,
a billion per acre achieved 85-90% control while
half that much resulted in half the control.
Steinernema life cycle
From: “Steinernematid and Heterorhabditid Nematodes”,
Southern Cooperative Series Bulletin 331, AK Ag. Exp. Stn.,
Fayetteville, AK 72701
Spot treatments effective for many pests
For control of fleas, applications should be made
to areas the pet frequents, such as feeding and
watering sites, beds, or shaded areas. When
treating tree pests, treat the drip line area, about
one-fifth of the total acreage. For tree bark pests,
nematode solutions are injected into borer holes.
When and how to apply
Soil temperature should be greater than 45º F to
apply all species and warmer for some. At that
temperature they will live but not grow very well.
When soil reaches 60º F all species will grow and
parasitize insects. Late evening or night is ideal
and never when the ground is hot and dry. Water
dry soils before applying. The best conditions are
cloudy, cool weather in spring or late summer
while soil temperatures are between 60º F and 85º
F. When using a sprayer, use a course nozzle,
remove screens and pressures can be set up to
300 psi. The mixture can also be distributed
through an irrigation system.
How it comes
Our 10, 25 and 50 million units come as a moist
powder sealed in a small Ziploc bag. We also carry
a 7 million unit in vermiculite.
Our larger bulk units come as water dispersible
polyacrylamide gel in trays. Our bulk OMRI listed
nematodes for organic production are packed in
trays of diatomaceous earth (DE).
Directions for mixing
Place powder, gel or DE in water and let it sit for
five minutes. Then stir nematodes and carrier into
a suspension in the water so you can sprinkle or
spray them on the ground. The suspended
nematodes survive about three to four hours
depending on temperature and oxygen in the
water, so mix only what you will apply today. They
will eventually drown in the water.
To illustrate in the case of a small backyard, use a
quart jar and a sprinkling can or hose-in sprayer.
Mix a 10 million nematode pack in 3 cups of water
in the jar. When fully suspended, pour 1 cup into
the sprinkling can or sprayer jug. Fill the sprinkling
can or sprayer jug with water. Spread or spray the
contents over approximately 13 ft2. Refill the
sprinkling or spraying container with the second
cup of suspended nematodes (swirl around before
measuring), fill with water, and cover the next 13
ft2. Finally pour the last cup of nematode
suspension, dilute in the sprinkling can or sprayer
jug, and cover the last 13 ft2. The amount of water
is not important so long as it allows you to spread
the total pack of 10 million nematodes over 500 ft2.
To mix half the quantity from a pack, use half and
leave half in the plastic bag and return to
refrigerator. There is a risk that the remainder will
dry out, so push the air out, seal it tight, and don’t
store long once the package is opened.
For nematodes packed in vermiculite, sprinkle the
carrier in the pots or soil surface, distributing 1
million nematodes over 50 ft2 or from 1,000 to
60,000 per 6 inch pot and water it in. Black vine
weevil in strawberries, for example, is controlled
using 10,000 to 20,000 nematodes per pot.
Agitate solution and keep soil moist
Agitate the water in the container while applying.
Keep the soil moist with light watering afterward to
help the nematodes move into the soil. Avoid overwatering
plants for one week after applying
nematodes as they may be washed out of the
media. To check viability, examine a drop of the
suspension with a hand lens. Live nematodes will
be curved and ideally moving in the water drop. If
dead, they are straight.
Easy and safe
Nematodes are easy to use and don’t harm
beneficial organisms, such as earthworms. They
don’t pollute and are harmless to us and our pets.
They are exempt from registration by EPA.