Editing Small tortoiseshell (section)

==Migratory patterns==
During migration, tortoiseshell butterflies position themselves in accordance with air currents; they only start migration at certain wind speeds. They are able to do this because of an extra sensory organ in their antennae. These butterflies have a developed [[Johnston's organ]] in their second antennae responsible for determining air currents in a number of other insects.<ref>Gewecke, Michael, and Monika Niehaus, (1981) "Flight and flight control by the antennae in the small tortoiseshell (''Aglais urticae'' L., Lepidoptera)." ''Journal of Comparative Physiology A'' '''145''' (2) (1981): 249–56</ref> Because their host plants, ''Urtica dioica'', grow in widely distributed areas, tortoiseshell butterflies tend to move around more than some other butterflies. These areas tend to be short thickets and shrubs.<ref name="Shreeve, T. G 1981"/>