[3] The sphinx moth Hyles lineata and anthomyiid flies also visit the flowers.

This species is notorious as one of the toxic plants most commonly responsible for livestock death, especially cattle fatalities on the rangelands of Colorado and Utah.

[11] Up to 15% of a cow herd can be lost to poisoning in areas where this larkspur and its hybrids are common.

[12] Abundance of larkspur has persuaded ranchers to remove their animals from some areas of rangeland, or use the land only at certain times of the year.

About two kilograms dry weight of the plant is estimated to provide a fatal dose of alkaloid.

[12] Toxicity reactions in animals, sometimes called larkspur toxicosis, can be treated with physostigmine.

[16] Glyphosate and picloram have been effective in research trials,[17] but these chemicals kill nontarget plants as well, accelerating the invasion of weeds into the habitat.