Immigrant species: A species which has arrived from somewhere else, generally another country, without the deliberate help of man. Founding individuals of immigrant species walked, flew, swam, rafted, were blown by high winds, or stowed away or hitchhiked in cargoes. Many immigrant pest insects arrive as stowaways in shipments of plants from other countries. Some of these insects are not detected and destroyed by inspectors, so there is a constant risk of arrival and establishment of pests from other countries (contrast with introduced species).