Nemasys® L Beneficial Nematodes

Nemasys L Steinernema kraussei beneficial nematodes help provide biological control of black vine weevil.

Nemasys L is based on the beneficial nematode Steinernema kraussei and provides a rapid curative control of black vine weevil. Nemasys L has the added advantage of being cold-temperature tolerant. Nemasys L will control black vine weevil larvae in soil temperatures down to 41°F. This means it will infect and kill black vine weevil larvae whenever they are active in the soil.

Nemasys L contains nematodes in their vigorously infective juvenile stage. These aggressive organisms actively seek out black vine weevil larvae and enter them through their natural openings. Once inside the larvae, they release symbiotic bacteria, quickly killing the insect pest. The nematodes then reproduce inside the insect and release a new generation of infective juveniles, which disperse in search of further larvae.

Nemasys L is a very robust nematode and can withstand higher environmental pressures than other nematode species; this makes it the product of choice when controlling black vine weevil in field and testing conditions.

Beneficial nematodes are microscopic worms that attack and kill targeted insects, without affecting any other organisms. Within the infected insect, the beneficial nematodes continually reproduce and then spread out for long-term control.


  • Effective against larvae at warm and low soil temperatures (41°F to 86°F)
  • Wide application window (early February to late November) whenever the larvae are active
  • Very robust, long persistence and survival in testing conditions
  • Active for up to 6 weeks after application
  • Infected larvae turn dark yellow

See our product instruction sheet for suggested application rates under our research library.

Package sizes include trays of 50 million and 250 million nematodes.

Always read and follow label directions.

Nemasys® beneficial nematodes are registered material for use in organic agriculture by the Washington State Department of Agriculture

Tips and Best Practices

This series of four videos on proper handling and application of Nemasys® beneficial nematodes is expertly presented by Jen Browning, Technical Service Representative at BASF. You’ll see Jen’s hands-on demonstration of biologicial controls in a greenhouse environment and learn valuable tips that you can integrate into your own operation. 

Nemasys® Beneficial Nematodes: Receiving, Storing and Checking the Viability

What should viable and live nematodes look like? What’s the proper way to refrigerate and transfer them? Watch a hands-on demonstration that covers the fundamentals and takes the guess work out of handling nematodes.

Nemasys® Beneficial Nematodes: Soil Application

Get the best result with your soil application by following these tips for ideal time, temperature, application equipment, proper settings and other valuable application tips.

Nemasys® Beneficial Nematodes: Foliar Application for Western Flower Thrips

What are the specific application tips for controlling Western Flower Thrips? Watch this demonstration of practices you can incorporate in your greenhouse.

Nemasys® Beneficial Nematodes: Best Management Practices

Are my biologicals working? Listen to Jen Browning’s answer to that and other frequently asked questions, including best practices for tank mix compatibility and building biological controls into your integrated pest management program.

Downloads and Resources

Labels, SDS and State Availability

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