I’ve seen my first Marsh fritillaries of the year, always a magical moment, except this year that magic was dulled somewhat by the fact that these particular butterflies in this particular location have obviously been introduced illegally, possibly as eggs or as larvae.

Expert opinion is that the site is too far from known populations of Marsh fritillary to have occurred naturally and, sadly for the butterflies (at least three individuals have been identified), the site does not have enough of the right habitat, so it is highly unlikely they will survive. (You can read more on the laws that apply to butterflies, including the Marsh fritillary, a fully protected species, on the UK Butterflies website.)