National Park Service

Northeast Temperate Network (NETN)

invasive animals


An invasive species is a non-native species (including seeds, eggs, spores, or other propagules) whose introduction causes or is likely to cause economic harm, environmental harm, or harm to human health. The term "invasive"; is used for the most aggressive species. These species grow and reproduce rapidly, causing major disturbance to the areas in which they are present. Some organisms, including insects, are referred to as alien invasive species or exotic invasive species. Put simply, these organisms were introduced, intentionally or accidentally, into an ecosystem outside their own and thrived.

How Alien Insect Species Are Introduced:

Accidental escapes - Sometimes an entomologist or naturalist accidentally has one of their collected specimens escape. Etienne Leopold Trouvelot, a Frenchman living in Massachusetts in the 1800's, unleashed a Lepidopteran beast in his own backyard. An amateur naturalist fascinated with silkworms, he brought some gypsy moth egg masses back from his native country. Some larvae escaped, and by the 1880's the caterpillars were defoliating his neighborhood. Today, over a century later, they feed on forests throughout the eastern U.S. and cost millions of dollars to contain.

Imported goods - Most alien insect invaders make their way to foreign regions by stowing away in imported goods or other transported items, like the wood-boring Asian longhorned beetle, which hid in wooden shipping pallets to make the overseas journey to America.

Intentional releases - Biological controls are sometimes released to control alien insect species, and when done correctly do not become invasive pests themselves. Some intentional introductions do cause problems, however. The Asian multicolored lady beetle was first introduced as a biological control in California in 1916; subsequent releases occurred in other U.S. regions for years after. The beetle is a voracious eater of soft-bodied insects like aphids, and went to work immediately. Unfortunately, the alien lady beetle out-competes our native lady beetle species, making their survival more challenging. In addition, the Asian lady beetles have a nasty habit of aggregating in homes and buildings during winter months, something our native species does not do.

Importance & Issues

jefferson salamander The presence and extent of invasive exotic species is a critical management concern at all network parks. Parks would greatly benefit from timely identification and removal of new invasive species. Catastrophic consequences to native species (loss of biodiversity and replacement of native flora and fauna) can result if this vital sign is not addressed. Invasive exotic species are a significant and growing stressor with clear ecological relevance to terrestrial systems within the NETN. This vital sign has relatively strong management implications via exotic species control programs. Numerous groups of invasive exotic species are of concern within NETN, including insect pests (currently only gypsy moths and hemlock woolooy adelgids are found in a few NETN parks) and pathogens, earthworms, and intertidal and aquatic fauna. Routine surveys for the presence/absence of particular invasive species should be mandatory at all parks. Lists of non-native species with the potential to invade individual parks already exist in most states and will be integrated into NETN protocols. These lists will identify the types of habitats to examine for invasion

Monitoring Objectives


Ensure the early detection of invasive animals in established forest monitoring plots and alert Park and state managers of any new incidences of invasive species in order to facilitate a rapid response.

Rocky Intertidal:

Ensure the early detection of invasive species in the intertidal resources of NETN parks and alert Park and state managers of any new incidences of invasive species in order to facilitate a rapid response.


Detection of non-indigenous species.



Monitor for emerald ash borer, Asian long-horned beetle; current spatial distribution and spread of hemlock wooly adelgid, exotic earthworms, European gypsy moth as well as eruptions of the native spruce budworm.

Rocky Intertidal:

Delineate intertidal zones, identify invaders and monitor relative abundance trends, exotic species extent and community composition.


Remote sensing and targeted presence/ absence surveys for particular invasive species.


Last Updated: December 30, 2016 Contact Webmaster