The study examines the effect of Sun and Moon characteristics on hourly light-trap catch of Agrotis segetum Den. & Schiff. (Lepidoptera, Noctuidae). A Járfás-type fractionating light-trap operated in Kecskemét, Hungary, between 1967 and 1969, from March to the end of November. This light-trap catch of insects separately every night from 6 p.m. to 4 a.m. (UT). We examined the data of the Turnip moth (Agrotis segetum Den & Schiff.) in connection with the characteristics of the Sun and the Moon.
There were working up the data of 5,712 moths in connection with the 11 characteristics of Sun and Moon. The following Sun’s and Moon’ characteristics were taken into account: Night sky polarization originated by the Sun and Moon, Gravitation potential of the Sun and Moon, Altitude of the Sun’s Arago- and Moon’s Babinet point above horizon, Collecting distance, Altitude of the Moon above horizon, Moonlight, Polarized moonlight. It was found that: The gravity of the Sun’s and the Moon’s has a greater effect than their night sky polarization. An important influencing factor is the position of the Sun’s Arago point above the horizon, but the Moon’s Babinet point has smaller effect. We have shown that higher values of polarized moonlight have a higher catch in the Last Quarter. A new result is that the reasons for the high catch in the First and especially the Last Quarter, in addition to the maximum value of polarized moonlight, are the maximum celestial polarization from the Moon and the maximum suction effect of gravity. Our most important new result is that the effect of the Sun on results of light trapping is stronger than that of the Moon, not only at dusk and dawn, but at all hours of the night.
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