The Danish zoologist Johan Christian Fabricius named this species in 1798, placing it in the genus Lygaeus.

[2] When the Italian entomologist Maximilian Spinola named the genus Arocatus in 1837, he designated Fabricius's Lygaeus melanocephalus as its type species.

[4] Lygaeus pruinosus, a nomen nudum referring to this species, was named by Eduard Friedrich Eversmann in 1837.

[19] Within Europe, it has been found in the countries Andorra, Austria, Belgium,[citation needed] Bosnia & Herzegovina, Bulgaria, Croatia, Czech Republic, France, Germany, Greece, Hungary, Italy, Moldova, Montenegro, the Netherlands,[21] Poland, Portugal, Romania, Russia, Serbia, Slovakia,[16] Slovenia, Spain, Switzerland, and Ukraine.

[22] Starting in 1999, A. melanocephalus has infested buildings in northern Italian cities, particularly in the regions of Emilia Romagna, Veneto, and Friuli-Venezia Giulia.

[17] Some Italian researchers believe this might be due to global warming, and that the insects enter buildings to escape the summer heat.

[4] In North America, A. melanocephalus have been found in the Canadian province of British Columbia,[26] and the American states of Washington, Oregon, Idaho,[19] Michigan,[27] Utah,[28] and Colorado.