Was just reading up on invasive pest species in North America and thought this is informative link on European Fire Ants. There is another link also under ants.
Myrmica rubra.
New insect species are always coming in through travel of human belongings, plant material, natural ability to migrate to new geographical location.
Climate change is allowing other non native creatures(which may include insects, plants and animals, viruses, bacteria, fungii) to be introduced into a climactic region that they would not normally be naturally occurring and now thrive.