This is a really charismatic group of aphids that specialize on sedges (e.g. Carex). There are species native to both Nearctic and Palearctic. I had the honor of collecting material for F.W. Quednau while he was working on a revision of the group (published in 2010), and consequently several of the slides in my collection were identified by him. I remember him nagging me gently to get species identifications on the Carex hosts I collected from, and me having tell him that I had no training in Carex, and that being so far from a university and a plant taxonomist precluded better Carex taxonomy. He seemed to grudgingly accept my excuse.
Iziphya spenceri Richards
This is one of the common species of Iziphya that I collect. It lives on sedges on dry slopes in the forests all along the western U.S. that I frequent, and it apparently is known from many other parts of the world in this kind of habitat.