Starting in 1999, repeated massive intrusions of the bug Arocatus melanocephalus inside urban buildings have been reported every summer in different locations in Northern Italy. This investigation, performed in the town of Modena, where the problem was particularly intense, by means of a survey and meteorological data series, showed a significant positive correlation between the intensity of insect outbreaks and the daily mean temperature increase. These findings suggest that current climatic warming might have affected the behaviour and/or population dynamics of A. melanocephalus and that building intrusions might represent an attempt to escape exceptionally high summer temperatures. (c) 2006 Elsevier Ltd. All rights reserved.