Jacobs-ladder - Polemonium pulcherrimum with a velvet mite (Balaustium sp.) by Jacob W. Frank

Meet Yellowstone’s Balaustium (Erythraeidae) velvet mite. They are identified by two canon-like structures behind the eyes called urnulae, which deploy noxious chemicals to defend against ants. Members of this genus are generalist predators in all life stages. This commonly encountered species can also persist exclusively on pollen, which is why they are often seen roaming sidewalks and buildings for wind-blown pollen. Original public domain image from Flickr