Beneficial Nematodes Hb+Sf Mix - Control Codling Moths, Fungus Gnats, Thrips & More

What the Hb+Sf Mix Targets

Heterorhabditis bacteriophora + Steinernema feltiae

Hb+Sf Together

• Borers: mint root borer
• Others: ticks

Sf Alone

• Fly Larvae & Maggots: fungus gnat (Sciarid) larvae, cabbage maggot, gall midge, humpbacked (phorid) flies, leafminers, onion maggot, root maggot
• Borers: lesser cornstalk borer, raspberry crown borer
• Others: thrips pupae, root aphids

Hb Alone

• Beetle Larvae (Grubs): blister beetle, May/June beetle, scarab, Japanese beetle
• Weevil Larvae (Grubs): citrus weevil, black vine weevil
• Borers: corn, grape root, peach tree, and squash vine borers
• Others: termites

Either Species

• Beetle Larvae (Grubs): asparagus beetle, Colorado potato beetle, cucumber beetle, white grubs
• Moth Larvae (Caterpillars): armyworms, codling moth, cutworms, garden webworm, hornworms, webworms
• Borers: general borers
• Weevil Larvae (Grubs): billbugs
• Fly Larvae & Maggots: crane fly (leatherjacket), fly larvae, house and filth flies, shore flies
• Others: ant queens, red fire ants, flea larvae and pupae

Heterorhabditis bacteriophora + Steinernema feltiae · How to Say It: het-er-oh-rab-DY-tis bak-teer-ee-OFF-or-uh, or just "Hb"; sty-ner-NEE-muh FEL-tee-eye, or just "Sf"

Grub, Fungus Gnat & Warm-to-Cool Soil Pest Control

Introduction to the Hb+Sf Mix

Soil temperature isn't the same all the way down. It shifts with depth, season, soil type, and even how much organic matter is breaking down beneath the surface, so a single lawn, greenhouse bench, or raised bed can have cool-season and warm-season pests at the same time. One nematode species built for a specific temperature range might not be as effective. Steinernema feltiae (Sf) stays active in cool soil, while Heterorhabditis bacteriophora (Hb) becomes active as soil warms. Blended together, they can provide effective coverage even when temperature or the weather shifts.

What Beneficial Nematodes Are

Nematodes are microscopic, unsegmented roundworms found in nearly any growing environment. Under a microscope they're translucent and slightly tapered, curling into an S or J shape at rest, and too small to see with the naked eye. Beneficial nematodes are entomopathogenic biological control agents. Instead of feeding on plant tissue, they hunt down insect pests directly, infect them, and let their symbiotic bacteria do the rest. That's the main difference between a beneficial nematode and the plant-parasitic kind that actually damages roots.

Two Temperatures, Two Depths, One Application

Hb and Sf split both the soil profile and the temperature range between them, rather than competing for the same territory or the same conditions:

• Sf, cold-active and shallow. Sf stays active in the upper few inches of soil or growing medium, and is more cold-tolerant, remaining effective down to about 46°F (8°C). The combination of shallow range and cold tolerance is what allows it to stay active through cooler shoulder-season conditions.
• Hb, deep-ranging once soil warms. As soils warm past about 61°F (16°C), Hb actively cruises into the deeper soil profile, tracking hosts rather than waiting for a pest to wander by. That is what makes it effective against grubs and beetle larvae that feed on roots well below where Sf nematodes roam.

Both species follow the same core life cycle. Eggs hatch into non-feeding juveniles, which molt into infective juveniles that hunt down a host, enter its body, and release bacteria that kill it within days. Juveniles feed on the cadaver, and the next generation of adults restarts the cycle. The difference is where each one searches and which temperatures it's active in.

When to Use the Hb+Sf Mix

This blend is great for when you're dealing with more than one soil temperature, more than one type of pest, or wide temperature changes. A few situations where that comes up:

Turfgrass and Lawns. Cool-season pests such as crane fly larvae and certain weevil grubs appear early, while warm-season white grubs like Japanese beetle and chafer grubs build up as soil warms. Sf works in cooler soil; Hb becomes more effective as temperatures rise, extending coverage across the season.

Greenhouses and Nurseries. Potted plants, growing benches, raised beds, and in-ground plots may have cold-tolerant fungus gnat larvae and warm-season root weevils in the same spaces. Since greenhouse temperatures fluctuate, combining nematode species that thrive in different temperature ranges can provide more consistent coverage.

Home Gardens and Mixed Beds. Vegetable, root-crop, and ornamental flower gardens may contain different pests with overlapping generations, including thrips pupae, root maggots, and small grubs. A broader temperature range helps cover pests that are active at different times.

Reapplication Note: Most Hb targets, like grubs, beetle larvae, weevils, and borers, run one generation per season, so one well-timed application can cover the vulnerable stage. Fungus gnats, ants, termites, fleas, and flies are the exception because they reproduce continuously or reinvade. Reapplication on roughly a monthly basis is recommended.

Pairing for Broad-Spectrum Soil-Pest Control

Hb+Sf covers the shallow layer and the deep root zone, so pairing it with a surface-level species closes the remaining gap.

• Steinernema carpocapsae (Sc) nematodes: works at the soil surface, in mulch and leaf litter, targeting fleas and small caterpillars.
• Triple Blend Mix: contains all three nematode species, Hb+Sc+Sf.
• Hypoaspis miles (Stratiolaelaps scimitus): a soil-dwelling predator in the top layer of soil that feeds on fungus gnat larvae and thrips pupae.
• Heterorhabditis bacteriophora (Hb) nematodes and Steinernema feltiae (Sf) nematodes: each species on its own, for pest pressure in just one zone.

Pairing for Above-Ground Emergence

Some pests spend part of their life cycle in the soil and part above ground.

• Orius insidiosus (Minute Pirate Bug) and Amblyseius cucumeris: target thrips once they've emerged from the soil onto foliage, while Sf handles the pupal stage in the soil below. Together, this covers thrips at both the soil and plant level. The Thrips Control Garden Pack bundles the Minute Pirate Bug, A. cucumeris, and Sf nematodes.
• Sticky Traps: the Thrips Trap Kit for adult thrips, or the Gnat Stix Traps / Arber Sticky Traps for adult fungus gnats.

Safe, Sustainable Pest Management

• Natural biological control with no synthetic pesticides
• Safe around people and pets when used as directed
• Safe for use on edible crops when used as directed, with no waiting period before harvest
• Fits seamlessly into existing IPM programs
• Requires no protective equipment

Application Rates

These are general starting points. Actual application should be adjusted based on pest species, plant type, and infestation severity. Monitor pest and predator populations regularly to gauge how well the program is working.

Soil Temperature Range

• Sf works best in soil about 57–79°F. It stays active down to about 46°F; below that it slows down but isn't harmed. Upper limit about 88°F.
• Hb works best in warm soil, about 66–91°F. It stays active down to about 61°F; below that it slows down but isn't harmed. Upper limit about 95°F.
• Beneficial nematodes need consistently moist soil. Avoid drying out.
• Keep soil moist for two weeks following application. Avoid runoff when watering.

How to Apply the Hb+Sf Mix

Apply indoors any time. Outdoors, stick to early morning, late evening, or a cloudy day; direct sunlight and UV rays kill nematodes. Wet the soil before and after application, and keep the ground damp for at least two weeks so the nematodes can move.

1. Prepare the Soil: Water the treatment area first. Nematodes move through water, so dry soil stops both species from reaching their targets, whether that's grubs feeding deep in the soil or fungus gnat larvae near the surface.
2. Mix the Solution: Combine the Hb+Sf mix with water between 59°F and 69°F. Water volume depends on treatment area size and infestation severity. Use the mixed solution within 1–2 hours; it stays viable up to 6 hours, but weakens the longer it sits.
3. Apply to the Soil: Distribute the mixed solution evenly using a watering can, pump sprayer, hose-end sprayer, or irrigation system, whichever you already have on hand. Full, even coverage isn't necessary, since nematodes move through the soil on their own from there.
4. Keep the Area Moist: Water lightly right after application, then maintain consistent soil moisture for two weeks. Avoid heavy watering that causes runoff, since that can wash nematodes out of the treatment zone.

Watering Can or Pump Sprayer

• Moisten the soil beforehand to avoid runoff and improve habitat.
• Mix 5 million nematodes with 1–5 gallons of water (59–69°F) to cover the desired area, diluting as needed for coverage.
• Water the treated area immediately after application and keep soil moist for two weeks.

Hose-End Sprayer

Use room-temperature water and let the nematode powder sit for 15 minutes to fully dissolve before spraying. Remove any screen filter first. Keep pressure at or below 72 PSI and use a nozzle 0.8 mm or larger.

Other Hose-End Sprayers (dial-style)

Use room-temperature water and let the nematode powder sit for 15 minutes to fully dissolve before spraying. Remove any screen filter first.

Pro Tips

• Hb+Sf covers shallow-dwelling fungus gnats and thrips pupae and deep-feeding grubs and beetle larvae in one application, across a wide temperature range. For fleas and other surface-active pests, Sc is the better fit. If you're not sure which pest you're dealing with, the Triple Blend Mix covers all three zones at once.
• Avoid flushing nematodes away by minimizing runoff when watering.
• Check for water retention and drainage in the areas to be treated to ensure watering is effectively penetrating the soil.

Chemical Compatibility

Some chemicals, including pesticides and fertilizers, can harm or even eliminate beneficial nematodes, reducing their effectiveness as natural pest controllers. To protect your nematodes, it's essential to check chemical compatibility before applying it to your soil.

To make it easier, we've created a detailed list of chemicals that work safely with beneficial nematodes, ensuring your garden stays healthy.

Before Activation

Your nematodes arrive in a bubble mailer with an ice pack. If your order includes other items or totals over $200, it ships in a free cooler in a 12×12×12 box. It's normal for the ice pack to have melted and feel warm on arrival; the product remains effective to use. If you're not applying right away, refrigerate the unopened package at 36–45°F in a dark place for no more than 30 days. Do not freeze.

After Activation

Apply the mixed solution within 1–2 hours. Nematodes stay viable up to 6 hours after mixing, but they sink and start to drown, so they weaken the longer they sit.

Why buy the Hb+Sf mix instead of a single species?
Because Sf and Hb are active in different temperature ranges and different soil depths, combining them extends the range of pest control beyond what either could do alone.

Can Hb and Sf really be applied together without one interfering with the other?
Yes. Both species use the same water-based application method and soil moisture requirements. They are compatible in the same mix and don't compete for the same hosts.

Can I use this mix alongside neem oil or insecticidal soap?
Yes, but timing matters. Apply nematodes a few days apart from any foliar spray, since some residue can affect nematode survival in the soil. The nematodes themselves pose no risk to your other treatments.

How often do I need to reapply?
It depends on the pest. Grubs, beetle larvae, weevils, and borers (Hb's targets) run one generation per season, so a single well-timed application usually covers the vulnerable window. Fungus gnats, ants, termites, fleas, and flies are different: because they reproduce continuously or reinvade, those need reapplication roughly every month for ongoing control.

Is this mix safe around edible plants, pets, and kids?
Yes. Both species are a natural biological treatment with no synthetic pesticides. They are safe around people, pets, and kids when used as directed, and safe on edible crops with no waiting period before harvest.

How long until I see results?
Beneficial nematodes start working once they're in moist soil.

I've heard nematodes can damage plants. Is that what this is?
No. That's a different, unrelated category: plant-parasitic nematodes (like root-knot nematodes) feed on roots and can genuinely harm a garden. Beneficial nematodes don't feed on plant tissue at all.

How do I know if a single species or combination is best?
Use these charts to narrow your search:

Beetle Larvae (Grubs)

Moth Larvae (Caterpillars)

Borers (Tunneling Larvae)

Weevil Larvae (Grubs)

Fly Larvae & Maggots

Miscellaneous Larval Pests

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We do not provide recommendations on pesticide use. Products are sold for home use only, not commercial use.

QUALITY GUARANTEE

If your beneficial insects or other perishable products are not viable when delivered, email info@naturesgoodguys.com within 48 hours of delivery with your order number and a description of the problem. Photos may be requested. Approved replacements ship on Wednesdays and Thursdays.

• Open your package right away and check for storage instructions. Some products need refrigeration, and improper storage voids the guarantee.
• Ice packs help moderate temperature in transit and are not expected to arrive frozen.
• Some insects need time at room temperature before they become active, and many are hard to see without magnification.

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