Pissodes sp. “Conifer Bark Weevil” Curculionidae

Lake Inez, MT
May 27, 2017
Robert Niese

Conifer bark beetles in the genus Pissodes are relatively common, harmless parasites of many tree species. In the east, however, they are a major threat to Eastern White Pine where they drastically reduce growth and recruitment of young trees.

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Cyphocleonus achates “Knapweed Root Weevil” Curculionidae

Missoula, MT
August 13, 2015
Robert Niese

These weevils are native to Europe, but were introduced in the 1980s as a potential biological control agent for various species of knapweed. Various studies have shown that they are actually quite good at reducing the biomass of Spotted Knapweed, and have been successful in various locations in Montana, Minnesota, Oregon, Nevada, British Columbia, and recently, Michigan.

Ceutorhynchus erysimi “Shepherd’s Purse Weevil” Curculionidae

Missoula, MT
June 19, 2015
Robert Niese

These adorable weevils were introduced along with the invasive weed, Shepherd’s Purse (Capsella bursa-pastoris; Brassicaceae) from Europe. They have iridescent green-blue elytra and rarely reach a size of more than 2mm. They’re my new favorite introduced species.