Mites appear on foliage in spring as Canada thistle plants bolt. Larvae, nymphs, and adults are white, tan, pink, or yellow, depending on the developmental stage. All stages are tiny (0.15–0.20 mm long) and best viewed with a microscope. Females exist in reproductive (summer) and overwintering forms. Feeding mites suck out the contents of leaf cells. There are multiple generations per year, and overwintering is likely on roots or root buds.