Vanessa cardui painted lady's migration pattern in northern Europe apparently does not follow a strict northwest heading. The range of headings suggests that migrating butterflies may adjust their migration patterns in response to local topographical features and weather, such as strong wind patterns. Laboratory-raised autumn-generation painted lady butterflies were able to distinguish a southern orientation for a return migration path. According to the same laboratory-based study, when butterflies were isolated from the sun, they were unable to orient themselves in a specific direction, opposed to those that did have access to the sun. This suggests that "V. cardui" requires a direct view
Brachycaudus cardui "B. cardui" are usually attended by ants which feed on the honeydew the aphids produce and drive away predators. Researchers found that in a damp meadow which contained ragwort ("Jacobaea vulgaris") but no ants, although winged "B. cardui" arrived at the site, they failed to establish colonies despite an abundance of the host plant. In an experimental habitat, colonies of "B. cardui" on "J. vulgaris" flourished when ants were present but died out if ants were excluded. Infestation with "B. cardui" causes the margins of affected leaves to roll up. This aphid is a vector of plum pox, a serious