Vanessa cardui migrations take place at high altitude, which explains why these migrations are seldom witnessed. "V. cardui" is known for its distinct migratory behavior. In California, they are usually seen flying from north to northwest. These migrations appear to be partially initiated by heavy winter rains in the desert where rainfall controls the growth of larval food plants. Painted lady migration patterns are highly erratic and they do not migrate every year. Some evidence suggests that global climatic events, such as el Niño, may affect the migratory behavior of the painted lady butterflies, causing large-scale migrations. Based on experimental data, the
Black and white Black and white Black-and-white (B/W or B&W) images combine black and white in a continuous spectrum, producing a range of shades of gray. The history of various visual media has typically begun with black and white, and as technology improved, altered to color. However, there are exceptions to this rule, including black-and-white fine art photography and in motion pictures, many art films. Most early forms of motion pictures or film were black and white. Some color film processes, including hand coloring were experimented with, and in limited use, from the earliest days of motion pictures. The switch from most films