These are tiny ladybeetles, and as the name suggests, they can vary in appearance. They are a European species introduced into North American presumably for aphid control as they are strongly associated with aphids. According to Bug Guide, they were first reported in North America from Quebec, Canada (Gordon, R.D. 1987. The first North American records of Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae). Journal of the New York Entomological Society 95: 307–309. JSTOR).