Why to introduced species thrive and multiply so easily in their new habitats

Actually depends on the species. Take snakes for example. They quickly thrived here in america because they had similar environements over in europe. The warm climate here in florida is perfect for them. They like the heat of the sun the dense foliage and many other good qualities here. Also their are other places that are good as long as they are hot have water and prey and a nice hole they can sleep in they can survive making them very adaptable.