Libellula is a genus of dragonflies, commonly called chasers or skimmers, in the family Libellulidae. They are distributed throughout the temperate zone of the Northern Hemisphere. Most species are found in the North America.
The Libellula are medium-sized dragonflies, with diagnostic dark triangular patches at the hindwing base, normally crossed by pale veins. They have 12-20 antenodal cross-veins, and is the only libellulid genus in Europe with always more than one cross-vein in each so-called bridge space (the long triangular space below the subnode).
Separation from other genera
Leucorrhinia is the only genus also with dark hindwing patches whose distributions overlap widely., but in these the patches are smaller and not pale-veined. Leucorrhinia species are also much smaller, have 7-8 antenodal cross-veins and bright white frons. Mature males of Diplacodes lefebvrii and Trithemis festiva have dark hindwing patches but are much smaller, sleeker and generally darker. Orthetrum species can be similarly robust and pruinose, but never have more than a slight yellow colouring at the wing base.
Separation of the species
Identification is best done by abdomen shape, wing patterns and body colours. The three widespread species also have rather different habitat preferences.
Males are aggressive and territorial and relentlessly chase off rivals with fast dashes after which they return to their preferred perches. They do not oviposit in tandem, but females are usually guarded by the male hovering overhead. However, L. fulva and probably L. pontica oviposit alone.