Biological Control

Cyphocleonus achates, knapweed root boring weevil

Biological controls are small insects that feed on noxious weeds, reducing their ability to reproduce and spread, they are an excellent tool to reduce large weed populations. These insects go through rigorous testing with USDA to ensure they will only cause damage to the intended target weed species.

Biological controls are available for the following weed species; Dalmatian toadflax, diffuse and spotted knapweeds, Russian knapweed, Canada thistle and common St. Johnswort.

Please contact the CCT Land Operations/Range Program to see if these insects would be right for your property. To have your name added to the list for FREE distribution as insects become available.

Larinus minutus - Flower seed head weevil

This biological controls will feed on the flower heads of knapweed, thus reducing the number of seeds the plant can produce.

Mecinus janthiniformis

Attacks Dalmatian toadflax plants by feeding as larvae in the stem of the plant and later emerging as adults and feeding on the foilage of the weed.

Urophora cardui- Canada thistle gall fly

Fly larvae impact plant vigor in Canada thistle by inducing the plant to divert energy away from root and flower production to produce gall tissue in stems.

Chrysolina spp. Klamath weed beetles

The larvae of this beetle feeds on the leaves of Common St. Johnswort.

Cyphocleonus achates

Knapweed root boring weevil. Damage by this insect is seen in the roots of knapweed plants.