Z is a freeware fly with variable behaviour patterns. Each fly is genetically unique and only lives when the pc it inhabits is on-line. Conceived as a virtual swarm, the flies are intended to multiply through the internet via free exchange between users. Individuals can communicate through canal Z according to different criteria: time zone, on-line flies, community evolution graph, swarm genealogical tree, language, etc. Z users can manipulate the behaviour and morphology of individual flies at Z.lab, the genetic laboratory. The resulting mutants can then be exchanged through canal Z. The aim of Z is to create a distributed communication network that is independent of any central server. Each fly will become both server and client simultaneously. Soon Z users will be able to create their own networks. Z evolution and phenomena are online at http://zexe.net and at canal Z.