Authors: Knop, Eva; Grimm, Majken;Liechti, Felix;

Insects are of increasing conservation concern as their abundance and diversity has recently been reported to decline. Most of what we know on their decline is derived from studies on insects close to the ground. Generally, we do not know much about high-flying insects, and accordingly also not much about factors driving their abundance. Here, we thus tested whether the abundance of high-flying insects differs between rural, urban and mountainous landscapes, whether their abundance is related to meteorological factors or the hour of the day. The abundance of high-flying insects was recorded using vertical-looking radar devices. Despite colder temperatures in mountainous regions and a clear positive relationship between high-flying insect abundance and temperature, we found the highest abundances in the mountainous regions. In contrast, in the lowlands, abundances did not differ between urban and rural landscapes. We conclude that land-use on the ground affects the abundance of high-flying insects, and that rural areas in the lowlands offer similarly poor conditions for high-flying insects as do urbanized areas. Conservation measures should therefore also account for the needs of high-flying insects.