- Leafy Spurge
- Knapweeds
- St. Johnswort
- Yellow Starthistle
- Musk Thistle
- Canada Thistle
- Tansy Ragwort
- Toadflax
- Poison Hemlock
- Purple Loosestrife
- Educational Materials
(insect photographs)
Knapweed Insects

Knapweed Root Weevil
Cyphocleonus achates

Our newest insect for the knapweeds is the Knapweed Root Weevil, Cyphocleonus achates. This large weevil lays approximately 100 eggs at the base of older/larger spotted and diffuse knapweed plants. The developing larvae mine the central taproot, damaging the weed's vascular tissue and cause root-gall formation. This root-boring beetle is doing a dramatic job against spotted knapweed. Don't wait another year, get to the root of your knapweed! $100./carton of 105 root weevils.

Another bio-control of spotted knapweed is the Blunt Knapweed Flower Weevil, Larinus obtusus. This beetle will establish itself readily and spread quickly through your knapweed. We've seen noticeable declines in knapweed seed production and increased plant stress due to this new insect.
Larinus obtusus
Blunt Knapweed Flower Weevil
Larinus obtusus

Pre-order your weevils now for July 2018 delivery!
$75./carton of 210 adult flower weevils.

Our third insect against spotted and diffuse knapweeds is the Lesser Flowerhead Weevil, Larinus minutus. This long-lived beetle lays its eggs throughout the summer on the flowers of both diffuse and spotted knapweeds. Like the other flower attacking agents, this species contributes greatly to reducing the production of new knapweed seed.

Both of the Knapweed Flowerhead Weevils are winter cold hardy and yet thrive in hot, dry summer knapweed environments. If you have spotted or diffuse knapweed, you should get some of these beetles released this year. Both the Blunt and Lesser Knapweed Weevils are compatible in your knapweed infestations. Cartons of 210 adults are $75.00.

Lesser Knapweed Flowerhead Weevil damage (left) and adults.

Click here for more knapweed information...

Biological Control of Weeds, Inc.
1418 Maple Drive • Bozeman, MT 59715
Phone 406-586-5111

Email: bugs@bio-control.com