One of the factors influencing the increased introduction of exotic insect species has been the increase inimportation of foreign products and materials. In absence normal natural enemy complex or of environmental constraints these introduced species may become pests and cause extensive damage to crops or livestock. Pests may also be transported to countries in which they are not indigenous by the introduction of new crop types or animal breeds, with similar results. In general, it is such changes in agricultural practices as the introduction of new crop species or enlargement and aggregation of fields, use of monocrops and plant density that have been held responsible for causing many pest problems. Risch(1987) cited