The Least Carpet (Idaea rusticata, or I. vulpinaria) is a moth of the family Geometridae. It is found in Europe.
The species has a wingspan of 19–21 mm. The length of the forewings is 9–11 mm. The adults fly at night from July to August, and are attracted to light. Of all moths in Britain it showed the greatest percentage increase in abundance during the period 1968 to 2007, and expanded its range beyond the vicinity of London.
^The flight season refers to the British Isles. This may vary in other parts of the range.