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
Urophora cardui Urophora cardui Urophora cardui or the Canada thistle gall fly is a fruit fly which, contrary to its common name, is indigenous to Central Europe from the United Kingdom east to near the Crimea, and from Sweden south to the Mediterranean. The Canada thistle gall fly has been introduced to North America from Europe to control the population of its host plant, Canada, or creeping thistle, which is an invasive, introduced weed in North America. The fly starts life as an egg, about one to thirty of them, laid on the stems of its host plant, the Canada thistle, "Cirsium