Abstract
We review the polarization vision of aquatic insects, which detect water from a distance by the horizontally polarized light reflected from the water surface. Reflection-polarization characteristics of different water bodies, as functions of sky conditions and solar elevation, are examined in relation to how they influence the detection of water bodies by polarotactic aquatic insects. Examples are given showing how aquatic insects can be deceived by, attracted to and trapped by highly and horizontally polarizing artificial reflectors, such as oil surfaces, horizontal black plastic sheets, asphalt roads, red or black car-bodies and black gravestones. We explain why mirages and polarizing black burnt stubble-fields do not attract polarotactic aquatic insects. The existence of a polarization sun-dial, which dictates the optimal time of day for dispersal by flying aquatic insects, is demonstrated. We finish by examining some unexpected aspects of polarization vision in insects: a polarotactic mayfly that never leaves the water surface and thus does not need polarotaxis, and polarotactic vision of several tabanid flies.