Infestazioni da Arocatus melanocephalus (Fabricius, 1798) (Heteroptera, Lygaeidae) nella città di Modena.

Arocatus melanocephalus is a small lygaeid which develops its life cycle on elm trees (Ulmus spp.). This heteropteran never aroused particular attention until summer 2001, when it suddenly started to become a problem for the inhabitants of Modena (northern Italy), owing to the repeated massive intrusions othis insect outside urban buildings during the summer. This paper gives information on the morphology and bio-ecology of this species and advances some hypotheses for the explanation of the phenomenon.