Odonata are hemimetabolic insects, which possess aquatic larval stages and terrestrial (aerial) adult stages. Larvae and adults are obligate carnivorous predators. Life cycles in Odonata are very diverse and constitute a major adaptation to the environment. In some species the life cycle is very short, with development times of 30 days and less; such species may complete two or more generations per year (multivoltine). They typically occur in temporary waters. Other species develop over several years, they may complete one generation in two or more years (partivoltine). Adults are excellent flyers, with extremely high manoeuvrability and often high flight speed. Some species are able to disperse over several 1000 km distance and cross oceans. The mating systems of Odonata are among the best studied and therefore Odonata are a model organism for sexual selection. Odonata are also commonly used as proxies for environmental changes and freshwater biodiversity. Odonata are among the oldest known insects and date back at least 325 Mio. years. Currently, ca 6,000 species are known globally, with another 1,000-1,500 still remaining undescribed.