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Migrations of dragonflies in Chokpak Pass of the Western Tien Shan (42.530°N, 70.605°E) were studied using large bird traps of the Rybachy type, which proved to be very efficient for recording these insects. The obligatory southward autumn migrations were proved for Sympetrum fonscolombii and Anax parthenope, and supposed for Hemianax ephippiger, which is a rare species in this region. The autumn movement from the mountains to plains was recorded for the species characterized by seasonal vertical migrations: Sympetrum arenicolor, S. striolatum pallidum, and Aeshna mixta. The cold air fronts increase the intensity of flights.

Previous work has suggested that dragonfly ocelli are specifically adapted to resolve horizontally extended features of the world, such as the horizon. We investigate the optical and anatomical properties of the median ocellus of Hemicordulia tau and Aeshna mixta to determine the extent to which the findings support this conclusion. Dragonfly median ocelli are shown to possess a number of remarkable properties: astigmatism arising from the elliptical shape of the lens is cancelled by the bilobed shape of the inner lens surface, interference microscopy reveals complex gradients of refractive index within the lens, the morphology of the retina results in zones of high acuity, and the eye has an exceedingly high sensitivity for a diurnal terrestrial invertebrate. It is concluded that dragonfly ocelli employ a number of simple, yet elegant, anatomical and optical strategies to ensure high sensitivity, fast transduction speed, wide fields of views and a modicum of spatial resolving power.