In cool temperate regions, there is one generation per year, with females active in the early summer and males and pre-diapausing females active in the late summer. Only mated females survive the winter. This is probably because unmated females cannot enter diapause.
In regions with moderate temperatures, there occurs a single annual reproductive cycle, marked by female activity in the early part of the year and male and pre-winter female activity towards the end of the summer. Only females that have successfully reproduced are able to survive the winter months, which is likely due to their reproductive status.