Invasive Species: A Brief Overview
October 26, 2018
Invasive Species: A Brief Overview
An invasive species is a nonnative (also known as an alien)
industries, such as agriculture and fisheries. Impacts can
species that does or is likely to cause economic or
include power outages, contamination of agricultural
environmental harm or harm to human health. The human-
commodities, spread of diseases, increased operating costs,
mediated spread of species has occurred throughout history.
loss of irrigation water, competition with native plants, loss
However, as society has become more globalized,
of sport game or endangered species, and ecosystem
opportunities for the spread of nonnative and invasive
disturbance. For example, among other impacts,
species have increased (e.g., trade shipments can carry
species and introduce them to many different regions of the
Burmese pythons (Python bivitattus) have multiplied in
world). In addition, changing environmental, ecological,
south Florida and prey on native species of reptiles,
and socioeconomic conditions could alter the risk for
birds, and mammals;
invasive species introductions in the future.
zebra mussels (Dreissena polymorpha) and quagga
Invasive species include terrestrial and aquatic plants,
mussels (Dreissena rostriformis bugensis) from Eastern
animals, and microbes. Their introduction—whether
Europe have clogged intakes for urban water supplies
deliberate or unintentional—can pose threats to native
and nuclear power plants in the Great Lakes and
animal and plant communities, can lead to ecosystem
compete with native species;
disruptions, and may contribute to extinctions of native
species. Invasive species also can directly cause or transmit
citrus greening (Candidatus Liberibacter asiaticus) or
threats to human health. The introduction and spread of
Huanglongbing, a citrus plant disease originating from
invasive species also can result in significant economic
Asia, is spread by disease-infected insects and infects
costs related to damages as well as management, mitigation,
citrus trees, threatening the U.S. citrus industry;
and recovery activities. As of 2011, researchers at Cornell
University estimated that approximately 50,000 nonnative
the light brown apple moth (Epiphyas postvittana), a
species have been introduced to the United States, with
native pest of Australia, has spread to the United States
potential related costs exceeding $100 billion per year.
and is causing damage to a range of commercial fruit
Inherent in any calculation of the costs of invasive species,
and vegetable crops; and
however, is valuation of economic and societal factors on
which expert opinion differs.
leafy spurge (Euphorbia esula) has reduced the forage
value of western grazing land, resulting in lower overall
Terrestrial and aquatic invasive species can cause
value to private landowners.
environmental degradation and threaten certain U.S.
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link to page 2 Invasive Species: A Brief Overview
Table 1. Estimated Federal Funding for Invasive Species Activities, FY2017, Enacted (dollars in thousands)
USDA
DHS
ACE
DOI
EPA
DOS
Other
Total
% Total
Prevention
116,630
920,338 30,963
11,077
59,000
994
273
1,139,275
38%
Early Detect. / Rapid
320,562
0
19,726
17,413
—
792
250
358,743
12%
Resp.
Control / Management
685,511
0
58,371
48,451
—
12,121 100
804,554
27%
Research
382,953
0
9,085
5,335
107
2,002
2625
402,106
13%
Restoration
91,479
0
13,302
18,890
0
0
199
123,871
4%
Educ. / Public Awareness
149,356
0
6,985
572
—
128
1115
158,156
5%
Leadership / International
2,475
0
1,851
2,000
0
2,454
69
8,849
<1%
Total
1,748,966
920,338 140,283 103,738
59,107
18,490 4,632
2,995,553
100%
% Total
58%
31%
5%
3%
2%
1%
<1%
100%
Source: CRS. Data from National Invasive Species Council (NISC), “Invasive Species Interagency Crosscut Budget,” January 25, 2018,
https://www.doi.gov/sites/doi.gov/files/uploads/crosscut_25january2018.pdf.
Notes: USDA (Dept. of Agriculture); DHS (Dept. of Homeland Security); ACE (Army Corps of Engineers); DOI (Dept. of the Interior); EPA
(Environmental Protection Agency); DOS (Dept. of State); Other includes Dept. of Transportation, National Aeronautics and Space
Administration, and Dept. of Commerce. Does not include funding for U.S. Agency for International Development. Data are self-reported by
the federal agencies engaged in these activities and are not independently compiled. According to NISC, values are conservative estimates of
agency expenditures on invasive species. Totals and percentages may not add up due to rounding.
Management
(16 U.S.C. §§4701 et seq.), and the Noxious Weed Control
Managing invasive species often involves multiple efforts
and Eradication Act of 2004 (7 U.S.C. §§7781 et seq.) are
throughout the stages of invasion (see text box). Prevention
tailored to species’ groups or habitats. Broad statutes also
of transport and/or introduction is the primary means to
can provide authority to address invasive species based on
avoid a new invasion. When an invasive species is
their impacts and include the Endangered Species Act (16
introduced, control efforts may involve eradication where
U.S.C. §§1531 et seq.), the Lacey Act (18 U.S.C. §42, 16
possible and, where not possible, efforts may reduce
U.S.C. §§3371-3378), and the National Environmental
populations to manageable or tolerable levels. Early
Policy Act (42 U.S.C. §§4321 et seq.).
detection and rapid response (often by federal agencies) to
eradicate invasive populations before they become
Federal Funding for Invasive Species Activities
established can be critical to manage invasive species.
Several federal entities share the responsibility to manage
invasive species. In FY2017, the U.S. government spent an
Federal Framework for Invasive Species
estimated $3.0 billion across a range of federal agencies and
Management
activities in an effort to prevent, control, and eradicate
Federal efforts to control invasive species have included
invasive species domestically (Table 1). Activities at the
both administrative and legislative actions. For example,
U.S. Department of Agriculture, including those related to
several executive orders (EOs) have provided an
agriculture, national forests, and the Animal and Plant
overarching federal framework to address invasive species.
Health Inspection Service, accounted for the bulk of federal
In 1977, President Carter signed EO 11987, which required
funding, nearly $1.7 billion (58% of total funds). Activities
federal agencies to restrict the introduction of “exotic
at the Department of Homeland Security, including border
organisms.” In 1999, President Clinton signed EO 13112,
protection and security, accounted for about $0.9 billion
which revoked EO 11987, extended federal requirements to
(31% of total funding). The remainder of federal funding,
address invasive species, and established the interagency
about $0.3 billion (about 11% of total funding), covered
National Invasive Species Council (NISC). NISC provides
activities across other departments and agencies, including
national leadership in addressing invasive species. It is
the Departments of the Interior and Commerce.
cochaired by the Secretaries of the Interior, Agriculture, and
Commerce. In 2016, President Obama signed EO 13751,
For more background, see CRS Report R43258, Invasive
which expanded the membership of NISC and increased the
Species: Major Laws and the Role of Selected Federal
responsibilities of federal agencies to prevent and respond
Agencies.
to invasive species.
R. Eliot Crafton, Analyst in Natural Resources Policy
Several statutes provide federal agencies authorities to
Sahar Angadjivand, Analyst in Agricultural Policy
address invasive species in the United States. The current
statutory framework includes broad environmental laws and
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laws that directly address invasive species. For example, the
Nonindigenous Aquatic Nuisance Species Act, as amended
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Invasive Species: A Brief Overview
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