These hardy seed head and root boring agents (Larinus spp. and Cyphocleonus achates) are showing stunning declines in plant density and vigor after only several years of establishment. They attack diffuse and spotted knapweeds. The best results occur where the both are present.
Knapweed seed head weevil
Larinus minutus/obtusus: These weevils are doing a great job in the
field. Larvae consume developing seeds. Adults feed on foliage and flowers.
$100 per release
Knapweed root boring weevil
Cyphocleonus achates: This relatively new insect is very large and hardy. These weevils do a great deal of damage to taproots, often killing attacked plants. This species is our top pick for spotted knapweed control.
$125 per release