Hemiptera (true bugs, cicadas, leafhoppers, planthoppers, aphids, scale insects, psyllids) are among the most numerous and diverse in morphology, biology, ecology and behavior insect groups, with vital ecosystems. Many of them are important in the base of the food chain. Others have economic significance as pests on fruit trees, vines, greenhouse crops and other agrocoenoses. Invasive alien species are the second most important cause of biodiversity loss in Europe and many of them belong to Hemiptera. This special issue of ZooKeys includes a collection of 26 papers presented during the 6th European Hemiptera Congress, which was held at Blagoevgrad, Bulgaria from 25th to 29th June 2012. Leading Hemiptera experts from 26 countries in four continents took part at the congress. The discussions were focused on general aspects of Hemiptera studies treating faunistics and biogeography of the Mediterranean Basin and Europe more generally as well as on taxonomy and phylogeny of Cicadomorpha, Fulgoromorpha, Heteroptera, Aphidoidea and Psylloidea; complex application of ecological, acoustic, genetic, palaeontological and behavioral methods; applied research and pest control. This special issue will be of great value for anyone interested in the biology of Hemiptera in general and of certain groups in particular, stimulating future research on this interesting group of insects.