Arthropod-borne infectious viral diseases continue to plague mankind and are not causally treatable. The source of infection is often unknown, and the initial symptoms of patients may be vague, merely influenzalike, though progression to severe disease and, potentially, death may follow. This review selects and presents five such diseases, borne by mosquitoes: Dengue and yellow fever of the tropics and subtropics; West Nile virus disease, St. Louis encephalitis virus disease,and disease caused by encephalitic California serogroup viruses, which all three affect inhabitants of temperate zones (but not limited to). These currently relevant diseases are described regarding transmission highlights, viral reservoir animals and mosquito vectors, symptoms, and regions affected, aiming at raising the preventive and early clinical awareness.