Unrelated species living in similar physical environments often are shaped by natural selection to have comparable morphological, genetic, physiological, or life history characteristics; they are said to evolve convergently. Convergence is a common feature of evolution and is particularly prevalent in parasites. We will examine two phylogenetically distant groups of parasites, the Siphonaptera and the bat flies. Both groups are bloodsucking ectoparasites, showing similar morphological trends, such as the development of combs, the reduction or loss of eyes, and the reduction or loss of wings. We will examine patterns of convergence on a morphological, molecular and ecological level and discuss them in the light of phylogenetic information.