Man has managed to distribute insects around the world more effectively than with any other class of animals. Many such insects, without the constraints of their original habitat, have become established as pests.
International transport and commerce and the movement of livestock and nursery stock have all been responsible for the introduction of noxious or destructive insects into new regions. For example, the importation and planting of a gift shipment of Japanese cherry trees in Washington DC in 1912 introduced in to the USA the oriental fruit moth which is now one of the most destructive pests of peaches in that country. An example of the economic consequences of introduction is provided by the spotted alfalfa aphid. It was introduced into California in 1954, and within four years it had spread throughout the length of that state, inflicting over $35 million in direct crop damage and in costs of control.
The rapid migration of a dangerous insect through the medium of commerce is well illustrated by the instance of the pink bollworm of cotton, native to India and the most destructive pest of cotton. In about 1908, bales of cotton which contained a very high proportion of infested cotton seed from India were sent to an Egyptian spinning mill. The Egyptian infestation was not discovered until 1910, when the worm was already well established in widely separated localities. In an attempt to improve cotton varieties for planting in the Laguna district of Coahuila, New Mexico, a cotton grower planted imported Egyptian cotton seed in a field near Monterrey, thereby introducing the pink bollworm to a new country. When this infestation was first reported in November 1916, the worm was found to have spread throughout the entire Laguna district. Surveys were begun in the vicinity of 11 cottonseed-crushing mills in Texas that had received seed from the Laguna area. By the end of 1917, infestations had been found in cotton fields adjacent to two of the mills. Further, an extensive infestation was found late in 1917 at Anahuac, Texas, on Trinity Bay. The latter spread was attributed to Mexican cottonseed that was washed far inland when the great storm of 1915 wrecked a Mexican steamship en route to Galveston, Texas. Thus in less than a decade a major cotton pest, through a series of intercontinental distributional leaps, was spread through commercial channels from Asia to Africa, and to the North American continent.