All About Beneficial Nematodes: When to Use Them and Why They Work
Oct 21, 2025
Plants look fine—until they don’t. Slowed growth, poor recovery, recurring pest flare-ups—these often trace back to insect stages developing in soil, substrate, or moist media. Larvae and pupae of fungus gnats, thrips, leaf miners, grubs, vine weevils, and cutworms quietly set the stage for damaging adults. Left unchecked, those adults emerge and feed, compounding the problem.
Solution: Beneficial nematodes. These microscopic organisms actively seek out and control pest larvae and pupae, breaking the cycle before it reaches foliage or roots. They work in greenhouse trays, interiorscapes, turf, and even hydroponic systems—without harsh chemicals, resistance risks, or residue concerns.
Why Use Beneficial Nematodes?
When pest pressure persists despite surface sprays, the issue often lies in the stages you can’t reach—larvae and pupae developing in soil, substrate, or moist media. Beneficial nematodes go where conventional strategies fall short, controlling pests before they emerge as damaging adults.
Signals that nematodes can solve:
Fungus gnat activity: Adults hovering near pots indicate larvae in media.
Thrips pressure: Foliar thrips mean pupae are hiding in substrate.
Fleas outdoors: Shaded lawn edges, kennel runs, and pet hangouts harbor flea larvae in soil/thatch.
Caterpillar feeding: Early larval stages on foliage or near soil surface can be suppressed with nematode sprays.
Root-zone decline: Slowed growth or poor recovery often links to soil-stage pests.
Recurring flare-ups: Sticky cards keep catching adults because the cycle isn’t broken.
Seasonal grub damage: Turf thinning or root loss points to beetle larvae feeding below the surface.
Key Advantage: Nematodes control larvae and pupae at the soil stage—and in high-humidity conditions, they can also be applied as a foliar spray for caterpillars. This flexibility makes them ideal for greenhouse trays, interiorscapes, turf, lawns, and even hydroponic systems. By penetrating soil and substrate, nematodes stop pest development where sprays and leaf-only tactics can’t reach, reducing resurgence and protecting plant health naturally.
What Are Beneficial Nematodes?
Beneficial nematodes are microscopic roundworms that naturally occur in soil and moist environments. They’re harmless to plants and beneficial organisms but lethal to targeted insect pests. Once applied, nematodes seek out hosts and release symbiotic bacteria that neutralize the pest within 24–48 hours.
What Are Beneficial Nematodes For?
Beneficial nematodes are used to control insect pests at their most vulnerable stages—larvae and pupae developing in soil, substrate, or moist media. They interrupt pest lifecycles before adults emerge, reducing pressure from fungus gnats, thrips, leaf miners, grubs, vine weevils, cutworms, and more.
Which Nematode Species Works Best for Which Problem?
Entonem (Steinernema feltiae)
Targets: Fungus gnat larvae, thrips pupae, leaf miner larvae.
Timing: Apply preventatively in propagation or at first adult detection.
Capsanem (Heterorhabditis bacteriophora)
Targets: White grubs (Japanese beetle larvae), vine weevil larvae.
Timing: Apply late summer/early fall when grubs are small and near the surface.
Larvanem (Steinernema carpocapsae)
Targets: Cutworms, armyworms, some beetle larvae.
Timing: Apply when larvae are active in soil (Sometimes as early as after the last frost).
| Species & Product | Primary Targets | Best Timing |
|---|---|---|
| Steinernema feltiae (Entonem) | Fungus gnat larvae, thrips pupae, leaf miner larvae | Apply preventatively in propagation or at first detection of adult pests |
| Heterorhabditis bacteriophora (Larvanem) | Japanese beetle grubs, vine weevil larvae, root weevils | Late summer or early fall when grubs are small and near the soil surface |
| Steinernema carpocapsae (Capsanem) | Cutworms, armyworms, some beetle larvae | Apply when larvae are active in soil during early crop establishment |
How Beneficial Nematodes Work
Once applied to moist media, beneficial nematodes move through the thin water film in soil or substrate, actively searching for insect hosts. When they locate a larva or pupa, they enter through natural openings and release symbiotic bacteria that quickly stop the pest—usually within 24–48 hours.
Inside the host, nematodes reproduce and create new infective juveniles that disperse to find additional targets. This cycle continues as long as conditions remain moist, providing ongoing control without chemical residues or resistance concerns.
Benefits of Using Beneficial Nematodes
Beneficial nematodes provide a safe and sustainable solution for pest control. They do not harm plants, people, pets, or pollinators, making them ideal for integrated biological programs. By targeting larvae and pupae where sprays cannot reach, nematodes interrupt pest lifecycles and prevent adult outbreaks. Their biological mode of action eliminates resistance concerns, ensuring long-term reliability. Nematodes are easy to apply with drenches, injectors, sprayers, or watering cans, and they work in soil & substrate without the issue of leaving of chemical residues.
Top Use Cases for Beneficial Nematodes
Beneficial nematodes are effective in virtually every growing context. They control fungus gnat larvae and thrips pupae in houseplants, interiorscapes, greenhouses, nurseries, and hydroponic setups—anywhere these pests occur. They also suppress leaf miner larvae, vine weevil larvae, grubs, cutworms, and armyworms across ornamental crops, fruit and vegetable production, container plants, and outdoor landscapes. Nematodes are widely used in turf, lawns, golf courses, and sports fields for grub and flea control. They fit seamlessly into propagation programs, bedding plant production, and specialty crops like berries and ornamentals. Wherever pests develop in moist media or soil, nematodes deliver targeted biological control.
Examples of Use Cases:
Houseplants & Interiorscapes: Fungus gnat suppression; thrips support.
Greenhouse Ornamentals: Bedding plants, propagation trays.
Outdoor Ornamentals & Turf: Seasonal grub and weevil control.
Fruit Crops: Targets soil stages of pests like Tuta absoluta.
Tip: If controlling mobile or flying pests like thrips or fungus gnats with nematods, pair with yellow sticky traps to monitor adult pest pressurYou neee while nematodes tackle soil stages.
Timing Matters for Maximum Effectiveness
Apply nematodes when pests are in their vulnerable soil stages:
Preventatively: Before pressure builds, especially in propagation and young plant stages.
At First Signs: Sticky cards show adult fungus gnats or thrips → soil stages are already present.
After Media Disturbance: Following transplant or potting, when roots are vulnerable.
Ideal Conditions for Application:
Moist growing media (not waterlogged)
Moderate temperatures (50–86°F; Capsanem works down to 5°C)
Low UV exposure (apply early morning, evening, or on cloudy days)
Timing Reference For Common Seasonal Challenges:
Japanese Beetle Grubs: Treat late summer/early fall when larvae are small.
Fungus Gnats: Apply at first adult detection for maximum speed in cleaning up a problem, for situations where fungus gnats are experienced on a reocurring basis, Entonem is great at any time.
Vine Weevils: Apply in fall and spring when larvae feed on roots.
Compatibility & Storage
Do Not Mix With: Nematicides, strong oxidizers, or hydrogen peroxide products.
Storage: Refrigerate at 38–42°F; never freeze. Use before expiration date.
Agitation: Keep solution agitated during application to prevent settling.
FAQ: Beneficial Nematodes
What’s a nematode?
A nematode is a microscopic roundworm found in soil. Some are plant-parasitic (like root-knot nematodes), while others are beneficial for pest control.
Are beneficial nematodes safe for houseplants and gardens?
Yes. They’re safe for vegetables, fruits, ornamentals, and lawns—no harm to plants, people, pets, or pollinators.
Do beneficial nematodes kill fungus gnats?
Yes. Steinernema feltiae (Entonem) is highly effective against fungus gnat larvae in soil.
Can nematodes control grubs and fleas?
Yes. Heterorhabditis bacteriophora (Capsanem) targets grubs, and certain nematodes are used for flea control in lawns.
How do you apply beneficial nematodes?
Mix with water and apply as a soil drench using a watering can, injector, or sprayer. Keep soil moist for 2–3 weeks after application.
Do nematodes work in hydroponics or soilless media?
Yes. They thrive in moist environments, including hydroponic setups and soilless mixes.
How long do beneficial nematodes live in soil?
Several weeks under moist, moderate conditions. Reapply every 2–3 weeks to keep pressure down when experiencing moderate cyclical pressure, for knockdown of an active problem we recommend 3 applications, 3 weeks in a row.
Ready to Put Nematodes to Work?
When problems emerge from underground, the solution should meet it there. Beneficial nematodes are a smart, natural way to protect plant health at the root, reduce pest pressure, and keep things thriving.
Shop all Nematodes
