Most central Honshu populations of the ladybird beetle, Coccinella septempunctata L., pass the winter as quiescent adults. However, variations in life cycle within populations have been observed: hibernating and reproductive adults simultaneously coexist in the same habitat in winter. We studied microhabitat use patterns of this beetle in winter on a sunny slope of a southeast-facing riverbank. We found that, even though natural substrates were available, the beetle preferred to use artificial substrates such as metal cans (iron or aluminum), papers, and wooden materials discarded on the slope as oviposition and pupation sites. The artificial substrates were relatively easily warmed by solar radiation and were therefore used as thermal microhabitats by the beetle. Although ambient winter air temperatures of this region were not high enough for the beetles to complete their development, the use of thermal microhabitats enabled them to do so by thermal conduction. Prey aphids were also abundant during the winter. Thermal microhabitat use enables these beetles to complete an additional generation in winter.