APHIS Factsheet

Plant Protection and Quarantine October 2006

Invasive Species 

and Forest Health

Over the last 200 years, several thousand foreign 

plant and animal species have become established in 

the United States. While not all introduced pests are 

problematic, scientists estimate that one in seven is 

invasive. An invasive species is a nonnative species 

whose introduction into the United States causes, or is 

likely to cause, economic or environmental damage or 

harm human health. If such a pest escapes detection 

upon entry into this country, several years typically 

lapse between arrival and discovery—time the pest 

spends getting established in the environment. 

 In today’s global marketplace, the volume of 

international trade brings increased potential for the 

introduction of foreign pests and diseases that may 

threaten the health of U.S. forests and agricultural 

resources. Many of these invasive pests have seriously harmed urban and rural landscapes and have 

caused billons of dollars in revenue losses and 

cleanup costs in the millions. 

 Invasive species impact human health, the environment, and the economy of the Nation. Forest 

health and productivity are also at great risk as wildfire 

occurrences have been linked to increased invasivespecies infestations. Economic impacts in the United 

States from invasive species are estimated by some 

scientists to exceed $1 billion annually, in addition to 

negatively affecting hundreds of millions of acres of 

native ecosystems and associated native plants and 

animals.

 The natural migration of nonnative agricultural 

and forest pests into the United States is uncommon. 

Most species get into the United States from foreign 

countries through the international movement of 

people, commodities, and their conveyances. 

 For example, the Asian longhorned beetle, first 

discovered in New York City in 1996, was most likely 

introduced on wood packaging material (WPM) from 

China. This beetle is a serious threat to hardwood 

trees and has no known natural predator in the United 

States. To inhibit this specific beetle and other similar 

forest pests from entering the United States, the U.S. 

Department of Agriculture’s (USDA) Animal and Plant 

Health Inspection Service (APHIS) now requires 

that all WPM imported into the United States be 

heat treated or fumigated prior to departure from the 

exporting country. 

APHIS also requires that each shipment be accompanied by a phytosanitary certificate, issued by the 

exporting country, verifying that the WPM has been 

treated. 

National Invasive Species Council

On February 3, 1999, the President signed Executive 

Order 13112, requiring coordination and enhancement of Federal activities to control and minimize 

the economic, ecological, and human-health impacts 

caused by invasive species. That order also established the National Invasive Species Council (NISC) to 

coordinate the activities of the various Federal departments and agencies dealing with invasive species in 

the United States. NISC was tasked with facilitating 

an overall Federal strategy for minimizing the impact 

of invasive species. NISC members produced a 

management plan to improve coordination, prevention, 

control, and management of invasive species. More 

information can be found on the NISC Web site at 

<http://www.invasivespecies.gov>.

APHIS’ Role: Prevention, Detection, and Response

This Executive Order and the National Invasive 

Species Management Plan support the mission of 

USDA–APHIS to prevent new pests and diseases 

from becoming established in the United States.

 APHIS focuses on reducing pest risks to the 

United States, making certain that agricultural 

products entering the country do not carry invasive 

pests, conducting aggressive domestic surveillance 

programs, and ensuring robust emergency response 

capabilities in the event of a significant pest introduction.

 APHIS’ Offshore Pest Information Program (OPIP) 

performs the essential function of collecting, assessing, and reporting relevant pest and disease 

information from foreign countries. OPIP work is done 

by APHIS safeguarding officers stationed overseas. 

These officers gather critical pest information and 

monitor trade trends. They look for any changes in 

production, processing, and shipping practices that 

could increase the risk of pest introductions into the 

United States. That information assists in making

policy decisions, such as where risk assessments 

should focus, when to modify port-of-entry inspection, 

when to initiate rulemaking for certain commodities, 

and what pests APHIS should be surveying for at 

home. 

 
 As a means to combat many invasive species, 

organisms such as insects, fish, snails, plant pathogens, and nematodes are intentionally imported into 

this country to help provide natural control. Because 

some of these organisms can themselves be harmful, 

APHIS manages a permitting system to assess the 

potential risk they pose to plants, animals, and the 

environment. APHIS has biological scientists skilled 

in making the necessary risk assessments before 

such organisms are allowed into this country. 

 In addition to import permits, APHIS requires 

shipments of approved imported commodities to be 

accompanied by official sanitary or phytosanitary certification, which indicates that any pest or disease risk 

has been sufficiently mitigated. APHIS also requires 

that certain approved commodities undergo and pass 

preclearance inspection in the country of origin before 

being shipped to the United States. APHIS may also 

require that commodities undergo treatment—such as 

fumigation or temperature treatments—and/or mandatory quarantine prior to being allowed entry into the 

United States. 

 Once they have passed through these overlapping offshore protections, shipments must be cleared 

upon arrival in the United States. In March 2003, 

responsibility for port inspections of agricultural 

commodities transferred from USDA to the U.S. 

Department of Homeland Security’s (DHS) Customs 

and Border Protection (CBP). CBP has 1,800 agricultural specialists dedicated to inspecting agricultural 

commodities and other products that may be harboring pests and diseases. Under the legislation that 

created DHS, APHIS maintained the responsibility for 

establishing the regulations and guidelines that 

govern the import of agricultural and forest products, 

and CBP became responsible for conducting the 

actual inspections at the ports.

 APHIS recognizes that there is also risk posed by 

smuggled or improperly imported agricultural products 

and uses its Smuggling Interdiction and Trade Compliance (SITC) officers to address this vulnerability. 

APHIS’ SITC program is responsible for intelligencegathering and other antismuggling activities, such as 

secondary market and warehouse inspections, that 

help prevent animal and plant pests and diseases 

from entering the United States. When SITC personnel identify a smuggled product, they not only remove 

it from the market but also conduct a full investigation 

to identify and eliminate any illegal pathways at their 

source.

 APHIS has a strong domestic surveillance infrastructure in place to detect any pests that could slip 

past its prevention measures. The agency utilizes a 

nationwide system of experts to track plant pests of 

concern. The Cooperative Agricultural Pest Survey 

(CAPS) is a pest-surveillance program managed 

cooperatively by APHIS and State departments of 

agriculture, as well as universities, industry groups, 

and natural-resource protection organizations.

 The primary function of the program is to survey, 

identify, and monitor pests of concern to U.S. agriculture and the environment. Located in all 50 States 

and three Territories, CAPS program personnel track 

more than 400 pests of concern in both rural and 

urban sites nationwide. 

 In conjunction with APHIS’ prevention and surveillance efforts, the agency acknowledges the absolute 

necessity of being able to respond swiftly and in a 

coordinated manner should a serious pest or disease 

be detected. APHIS has the authority under the Plant 

Protection Act and the ability to respond quickly and 

effectively to identify new pests. In addition, APHIS 

has specific emergency response guidelines for 

many of the invasive pests and diseases that pose 

a significant threat to the United States. APHIS has 

developed these response plans in conjunction with its 

Federal, State, and local partners and conducted exercises to test such preparedness. To ensure maximum 

speed and effectiveness, APHIS has rapid-response 

teams stationed around the country ready to travel to 

detection sites to coordinate Federal containment and 

eradication efforts.

Examples of Invasive Forest Pests in the United 

States

Both natural ecosystems and those modified for agriculture and forestry are vulnerable to invasive pests. 

APHIS protects not only agriculture but also forest, 

rangeland, and wetland ecosystems. APHIS works 

closely with USDA’s Forest Service (FS) and the U.S. 

Department of the Interior’s Bureau of Land Management, National Park Service, and U.S. Fish and 

Wildlife Service.

 APHIS and the FS set the foundation for cooperative work many years ago to slow the spread of the 

gypsy moth and continue to work together on controlling and eradicating other invasive forest pests. The 

following examples illustrate the range of threats to 

forest health that APHIS, FS, and their partners are 

currently facing. 

Asian Longhorned Beetle

The Asian longhorned beetle is a serious threat to 

hardwood trees and has no known predators here. It 

has been detected in New York, Chicago, New Jersey, 

and in warehouses in several other U.S. cities. APHIS 

recently deregulated this pest in Chicago, and control 

activities in New York and New Jersey are proceeding. 

If the ALB were to expand beyond quarantined areas, 

it has the potential to wreak havoc nationwide, affecting such industries as lumber, maple syrup, nursery, 

and tourism and costing more than $41 billion in 

losses. APHIS has implemented new regulations for 

incoming solid WPM that will minimize the likelihood 
of the Asian longhorned beetle’s being re-introduced 

into the United States in the future. 

Emerald Ash Borer

In July 2002, the emerald ash borer (EAB) was discovered to be killing thousands of ash trees in southeastern Michigan. Evidence suggests that the beetle 

first entered Michigan from China at least 10 years 

ago, presumably from solid WPM or dunnage used to 

transport manufactured goods. The EAB was subsequently found in Ontario, Canada, and the States 

of Ohio, Indiana, Illinois, and Maryland. This pest 

spreads naturally by flying and through the transport 

of infested ash firewood, logs, lumber, and nursery 

stock.

 To limit human-assisted spread from currently 

infested areas, strict regulations are imposed on the 

transport of ash trees and ash wood products from 

those areas. In addition, national quarantines were 

imposed by USDA–APHIS and the Canadian Food 

Inspection Agency. Today, APHIS continues to 

focus on the critical mission of detection, control, and 

eradication. Regulatory and education and outreach 

activities are critical and offer the greatest opportunity 

to impact program outcomes while ongoing efforts 

from the EAB National Science Panel promise that 

more effective treatments and tools will eventually be 

available to combat EAB. USDA’s FS estimates that 

EAB, if not contained or eradicated, has the potential 

to cost State and local governments and landowners approximately $7 billion over the next 25 years 

to remove and replace dead and dying ash trees in 

urban and suburban areas. 

 

Phytophthora ramorum

P. ramorum—the fungus that causes sudden oak 

death—was first reported in 1995 in the woodland 

environment in central coastal California. The pathogen has a broad range of hosts, including hardwoods, 

softwoods, nursery plants, and shrubs. During the 

spring of 2004, the California Department of Food and 

Agriculture confirmed the presence of P. ramorum in 

two large wholesale production nurseries. Investigations and shipping records revealed that these nurseries had shipped large quantities of several common 

household plant varieties nationwide. 

 Through ongoing surveys of nurseries, APHIS 

continues to define the extent of the pathogen’s 

distribution in the United States and limit its artificial 

spread beyond infected areas through quarantine 

and a public education program. APHIS regulations 

were published on February 14, 2002, to control the 

movement of P. ramorum from 12 infested counties in 

California and an area under eradication in Oregon. 

A national survey is underway. Research being conducted by universities, USDA’s Agricultural Research 

Service and FS, and other scientists is aimed at better 

identifying hosts, methods of detection, and effective 

treatments. The potential threat to the commercial 

timber industry could exceed $30 billion if P. ramorum

became established in Eastern deciduous forests.

Sirex noctilio

Sirex noctilio, an exotic woodwasp, was detected in 

New York in 2004 through APHIS’ CAPS program. 

This pest has the potential to cause severe damage 

to North American pine forests, especially if it reaches 

the South. Scientists estimate that S. noctilio can 

spread at least 25 miles per year naturally. Twentyfour counties in upstate New York and two counties in 

Pennsylvania have positively confirmed the presence 

of this pest. APHIS and its cooperators are currently 

evaluating long-term options for mitigating this situation. In other countries where S. noctilio has been 

inadvertently introduced, scientists have identified a 

promising biological control agent for use against this 

pest. In support of the potential future 

biological-control program, APHIS is preparing a 

biological assessment and an ecological assessment. 

Although the potential impact of S. noctilio on U.S. forests is unknown, there is concern that it could cause 

substantial economic loss.

Gypsy Moth

Introduced in Massachusetts in 1869, the European 

gypsy moth is a highly destructive insect of hardwood trees. Gypsy moths feed on the leaves of 

more than 500 species of trees and shrubs. APHIS’ 

goal is to define the extent of the gypsy moth infestation and limit its artificial spread beyond the infested 

area through quarantine and an active regulatory 

program, including spot eradications. APHIS’ gypsy 

moth program regulates the movement of gypsy moth 

host-material from infested areas to other parts of the 

United States. This program is an extremely effective 

APHIS–FS–State partnership that prevents the establishment of gypsy moth in areas of the United States 

that are not contiguous to currently regulated infested 

areas. The Asian gypsy moth, which is very similar to 

the European gypsy moth, also poses a major threat 

to forest habitats in North America. 

Additional Information

For more information on invasive species, please visit 

APHIS’ Plant Protection and Quarantine Web site at 

http://www.aphis.usda.gov/ppq or USDA’s FS Web 

site at <http://www.fs.fed.us/foresthealth>. 

USDA is an equal opportunity provider and employer. 

United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture