Herbicides, bugs on plant strategies wrestle tenacious invasive weed

Cheyenne area rancher Nina Haas walked slowly in the range grass, lush from summer rain, looking down at Dalmatian toadflax plants, and stopped.

Something had grabbed her attention, and she went down to one knee for a closer look. “There,” she pointed to one of the leaves on a plant. A round hole had been bored through, one telltale indication of a Dalmatian toadflax stem boring weevil – Mecinus janthiniformis – at work.

As if coming out from behind a curtain on cue, a little black weevil with legs churning treaded from under a leaf and continued upward, oblivious to humans and going about fulfilling its USDA-mandated biocontrol job of munching and ultimately injuring the invasive plants on the range at the High Plains Grasslands Research Station just west of Cheyenne.

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