Yellow sac spiders are currently massively spreading over northern Europe. Our species distribution model suggests a much wider potential distribution of C. punctorium in northern Europe than currently observed. We predict a colonization of most of Germany, the Baltic States, Poland, Denmark, and southern Sweden. The yellow sac spider is the only venomous Central European spider whose bites frequently necessitate medical treatment. A yellow sac spider bite can be very painful and might even cause side effects such as nausea, vertigo, fever, and shivers (Sacher 1990; Weimann et al. 2011; Papini 2012; Nentwig et al. 2013). Although the C. punctorium venom is not life threatening and its bites are rare even in densely colonized areas (Sacher 1990), our predictions are nevertheless important, in that they highlight one of the consequences of global change. In addition to increasing reports of disease vectors expanding their ranges (Khasnis and Nettleman 2005), another problematic outcome of global change is the spread of venomous species into new territories.