Biotic homogenisation is considered among the greatest threats to global biodiversity. The rapid increase in introduced exotic species worldwide and the potential of these species to become invasive have now been widely recognised to have ecological and evolutionary consequences (Olden and Poff 2004; Olden et al. 2006). However, many accidentally or intentionally introduced species fail to establish in their new range. Of those alien species that do manage to establish many have negligible effects and some species, often those introduced with agriculture and forestry, are even considered beneficial and desirable (Williamson 1999). The impact of some invaders is unquestionably negative and as such they are designated as invasive alien species (IAS). Harmonia axyridis Pallas (Coleoptera: Coccinellidae),‘‘the most invasive ladybird on Earth’’, is undoubtedly one such species (Roy et al. 2006).

Ladybirds have a long history of use as biological control agents against pest insects (Majerus 1994). Indeed, the Australian vedalia ladybird, Rodolia cardinalis, was released in 1888 to control cushiony scale insects, Icerya purchasi, which were having devastating impacts on the Californian citrus industry (Majerus 1994). This ladybird, introduced as a classical biological control agent, established and drastically reduced the scale insect population. This marked the advent of modern biological control. Ladybirds are considered ‘‘flagships’’of biological control and their predatory habits have no doubt contributed to their popularity, particularly with gardeners. Ladybirds are one of the most loved insects worldwide but H. axyridis is extremely unpopular outside of its native range for a number