The effects of Brassica rapa stem color on the selection of host plants by Pieris rapae were investigated using choice tests between seedlings with reddish-purple, anthocyanin-containing stems and seedlings with light-green, anthocyaninless stems. The first landing response and the collective as well as the individual egg-laying behavior of P. rapae female butterflies to the reddish-purple-stemmed seedlings were comparable to the responses to the light-green-stemmed plants. These results demonstrate that stem anthocyanins do not play a significant role in host plant selection.