Background: Due to their abundance in some environments, the blood-sucking habit and the involvement in the transmission of several diseases, blackflies of the genus Simulium (Diptera: Simuliidae) can be considered among the most annoying biting arthropods.
Methods: Following repeated attacks to humans and animals, entomological investigations were carried out in green areas of Rome and surroundings. Site and period of attacks were reported, together with the human and animal reactions to the bites.
Results: Four Simulium species have been identified through morphological or molecular analysis: Simulium intermedium, Simulium lineatum, Simulium lundstromi and Simulium ornatum (complex). Larval breeding sites were identified in small moats, where a high density of blackflies larvae and pupae was revealed.
Conclusions: Being able to thrive in highly polluted water, even in few mm depth watercourses, some blackfly species are widely distributed in the area and their bites caused mild to severe reactions to humans and animals.