This paper presents 3 years of GIS‐based monitoring of western corn rootworm (WCR –Diabrotica virgifera virgifera LeConte), a pest which invaded Northern Italy in 1998. The Veneto Region established a regional monitoring network to detect this important quarantine pest and to employ an eradication programme. Data were collected by means of sex pheromone PAL traps and analysed by Indicator Kriging, a geostatistics tool that determines the probability of data values in a given area being greater than a defined threshold value. Geostatistical analysis proved to be effective in mapping the spread of WCR. The temporal sequence of the probability maps was useful in interpreting the expansion of the insect. The detailed description of the pattern of WCR presence in 2006–2008 proves the temporary and local efficacy of the eradication programme carried out up to the 2006 season in Venezia province. An interpretation of the spatial pattern of WCR between the 2006 and 2008 seasons suggests that the pest colonized the eradication area coming from other invasion fronts. The large‐scale pattern of WCR dispersion can be accurately described by the spatial approach, thus optimizing the monitoring and subsequent control of this important insect pest of Northern Italy. Other data analyses, based on stochastic interpolations and a demographical approach are in progress. An interesting perspective would be to build predictive simulation models based on climatic and agronomic data taking into account the spatial representation of WCR patterns.

1 The potato tuberworm (PTW) Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) is key pest of potato in tropical and subtropical regions. From 2002 onward, PTW has emerged as a problem in the Bologna province, the main potato production area in Northern Italy. 2 Field investigations were performed to study the temporal and spatial dynamics of PTW. Adult moths were monitored using pheromone-baited traps over 3 years (2009)(2010)(2011). Traps were georeferenced and catches were analyzed by geostatistical maps. Each year, the percentage of damaged tubers at harvest was assessed. 3 Pheromone trapping, integrated with temperature-dependent developmental times, showed that PTW completed two generations throughout the potato-growing season; the remaining generations developed in the noncrop season. Maps showed a clumped distribution of PTW at the landscape scale. The hot spots of infestation corresponded to the areas most intensively cropped with potato. Trap catches from hilling to harvesting were linearly and positively correlated with the percentage of damage in 2 out of 3 years and in the pooled data set. 4 The present study demonstrated the widening of PTW areal to Northern Italy. In this area, georeferenced pheromone traps were validated as a useful monitoring technique for describing the phenology and distribution of PTW, thus providing crucial knowledge for the rational management of this pest.