Why is the sky blue?

Cheyenne-area rancher Nina Haas walked slowly in the range grass, lush from summer rain, looked 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 at work.

As if coming out from behind a curtain on cue, a little black weevil with legs churning treaded from under a leaf. It continued upward, oblivious of the humans and going about  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.

Those attending the Dalmatian toadflax field day last month would later wave sweep nets and sweep the insects off plants. USDA workers used respirators