Invasive insects, plants, and diseases can have devastating impacts on the managed and natural environments into which they are introduced. Invasive organisms are those that are non-native, have high reproductive potential, and are not limited by biotic (predators, parasites, abundance of food items, etc) or abiotic (climate, etc) factors. In short, with high reproductive potential and few checks on population growth, these introduced organisms can displace native organisms, quickly dominate a landscape, disrupt natural food webs, and cause other types of habitat damage. Additionally, because it is estimated that most plant pests are non-native, control of these introduced pests is important in agricultural and forestry industries. Invasive pests can be introduced either intentionally or unintentionally. Unintentional introductions can occur when a pest escapes into the natural environment from a managed environment, or when the pest is an unknown stowaway on a transported good or vehicle. Many of the invasive pests that are introduced as a result of escaping from a managed environment occur among landscape plants. Initially planted in yards because of their attractive appearance and low-maintenance, these plants can quickly overrun and dominate natural environments, where they out compete native plants. This is why some formerly popular landscaping plants (purple loosestrife, burning bush, Norway maple) are on the list of prohibited invasive plants in New Hampshire. Plants are not the only organisms that can accidentally escape from a managed environment into a natural one. In the 1860’s, for example, an amateur entomologist in Medford, Mass., E. Leopold Trouvelot, was interested in introducing a silk industry to the U.S. He introduced the European gypsy moth when caterpillars that he had been rearing on a tree in his backyard wandered into the neighborhood. European gypsy moth has an extremely broad host range, and since its initial introduction has steadily spread across the U.S., resulting in expensive monitoring and control programs. Many unintentional introductions occur when a pest is accidentally brought into a new area on or in cargo—such as within packaging and shipping materials, in transported firewood, and within shipments of seeds and nursery stock. Such transported invasive pests can move into new areas much more rapidly than would otherwise be possible. The Division works with other state and federal regulatory agencies to oversee shipments to and from the State of New Hampshire to reduce potential introductions. The Division of Plant Industry oversees threats from invasive plants, insects, and pathogens primarily through the Invasive Species Committee, the cooperative agricultural pest survey (CAPS) program, and through regulating the nursery industry.

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