Biological Control Program

Biological control uses parasites, predators and pathogens to reduce another organism’s density to a level lower. Biological control is part of an integrated pest management approach. The TNRD provides biological control agents to private landowners within the TNRD free of charge to reduce invasive plant populations, and to prevent invasive plants spreading into new areas.

Biological control is suitable for invasive plant infestations where other management strategies are neither cost-effective nor environmentally desirable. A good example of such an area are large knapweed infestations in open grasslands or adjacent to water bodies where herbicide application is not allowed. 

Biological control agents (insects) weaken the target plant’s seed production and overall plan integrity by feeding on the seed heads, and other parts of the plant, such as their root systems.  Biological control will not typically get rid of your weeds all together, and its results are usually seen over numerous years. It is a long-term control strategy. 

Agents are available in the TNRD for the following  invasive plant species: 

  • Spotted knapweed
  • Diffuse knapweed
  • Dalmatian toadflax
  • Leafy spurge
  • St. John’s Wort
  • Select thistle species

Insects will be made available upon available resources, on a first come first serve basis and will be delivered based on the timing of the insects emergence throughout the summer months

Additional Resources

How to Apply

Contact us to request biological control insects.

Thompson-Nicola Invasive Plant Management Committee


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