Navigation is important to Lepidoptera species, especially for those that migrate. Butterflies, which have more species that migrate, have been shown to navigate using time-compensated sun compasses. They can see polarized light, so can orient even in cloudy conditions. The polarized light in the region close to the ultraviolet spectrum is suggested to be particularly important. Most migratory butterflies are those that live in semiarid areas where breeding seasons are short. The life histories of their host plants also influence the strategies of the butterflies. Other theories include the use of landscapes. Lepidoptera may use coastal lines, mountains, and even roads to orient themselves. Above sea, the flight direction is much more accurate if the coast is still visible.