Why do highly polarizing black burnt-up stubble-fields not attract aquatic insects?
Kriska G; Malik P; Csabai Z; Horvth G Group for Methodology of Biology Teaching, Eötvös University, H-1117 Budapest, Pázmány sétány 1, Hungary. Horizontal black surfaces are usually very attractive to polarotactic aquatic insects, since they generally reflect highly and horizontally polarized light, and thus imitate water surfaces. We monitored highly polarizing black burnt-up stubble-fields, but surprisingly never found aquatic insects or their carcasses in the ash, although flying polarotactic insects were abundant in the area, which we showed by attracting them to horizontal black plastic sheets. To explain this observation, we measured the reflection-polarization characteristics of burnt-up stubble-fields in the red (650 nm), green (550 nm) and blue (450 nm) parts of the spectrum at three directions of view relative to the solar meridian. We established that (i) the degree of linear polarization p of light reflected from the black ash is high; (ii) p is the higher, the darker the a
