Stages of Development of Dragonfly Larvae Libellula depressa (Odonata, Libellulidae) in the Central Caucasus

Libellula depressa L. dragonfly larvae inhabit aquatic biotopes of the plain, foothill and mountain zones of the Central Caucasus up to 1700 m above sea level, no more than 30 cm deep with silty and detrital deposits. The onset of metamorphosis and emergence of adults begins when the water warms up to 18 ± 1°C in all zones, accompanied by a shift in the time of their onset from April on the plain to mid-June in the mountains. In their development, the larvae go through 14 age stages. The development time of larvae is within 76–110 days, taking into account the egg phase – 101–137 days. The increase in the development period begins with the 7th stage, the longest is the last 14th. Development is characterized by the formation of complexes of morphological and linear features that reliably determine the stage. Morphological changes affect significant systematic features that appear or are lost at a particular stage. Seven age groups include 1–4 with common morphological parameters.

larval stages, development, ecological features, distribution, morphological features, ontogeny