Procambarus clarkii is an invasive, prolific and aggressive species introduced into Italy for commercial use since the 1980s. In November 2010, this red swamp crayfish was detected in Lake Orta, a large, deep, Italian subalpine lake. Well-known for its 80-year heavy pollution by copper, Lake Orta has been gradually colonized by biota, after its chemical recovery in the 1980s. The lake is still far from being comparable to other subalpine lakes for taxa composition and seasonal dynamics. Lake Orta may be regarded as an unstable environment, in which the invasion by this voracious species deserves particular attention. After the present early detection, we plan to perform interventions to minimize negative impacts of P. clarkii to both the ecology and economy of the region. The latter may be particularly important in the case of the Lake Orta because of a persistence of heavy metals in the sediments.