The impact of invasive species in the United States is widespread, and their consequences for the economy and the environment are profound. Invasive species are nonnative plants, animals, and microorganisms intentionally or unintentionally brought into a new environment. Once in that new location, these species may be able to crowd out native species, multiply at a rapid rate, and spread to other locations. These invaders can also affect people’s livelihoods and pose a significant risk to industries such as agriculture, ranching, and fishing. The cost to control invasive species and the cost of the damages they inflict are estimated at billions of dollars annually. With respect to our nation’s forests, the history of harmful invasive species is long. For example, starting in the early 1800s, American chestnut trees were devastated by a succession of two nonnative pathogens—ink disease and chestnut blight. Chestnut trees were a major component of the nation’s deciduous forests, were valuable to wildlife, and had wide use as a source of lumber. Today, chestnut trees still survive in much of their former range, but only as sprouts from the old root systems. The gypsy moth is another serious invasive forest species that continues to harm our nation’s forests more than 130 years after its accidental release by an amateur entomologist studying silkworms. Each of the three forest pests we reviewed in our April report likely entered our country in the last 20 years. The Asian longhorned beetle likely entered in the mid-1980s, currently infests areas in Illinois, New Jersey, and New York, and affects hardwood trees such as maple and elm. The emerald ash borer likely entered the United States in the early 1990s and infests about 40,000 square miles in Indiana, Michigan, Ohio, and some parts of Canada. A small infestation was confirmed just last week in Illinois. The borer affects all 16 species of North American ash trees. It is thought that the pathogen that causes Sudden Oak Death, P. ramorum, entered the country as early as the mid-1990s, although how it arrived is unknown. Of the three pests we reviewed, P. ramorum affects the widest range of species, including various species of oak and ornamental plants such as rhododendrons and camellias. The pathogen has affected more than 19,000 square miles in California and one county in southwestern Oregon. Together, according to USDA, these forest pests have the potential to cause the loss of trees valued at trillions of dollars. APHIS is the lead federal agency responsible for responding to insects and diseases that have entered the country and that might harm U.S. agriculture. APHIS conducts detection surveys, issues quarantines, directs eradication efforts such as removing infested trees or applying pesticides, develops control technologies, and performs public outreach. The Forest Service—which has federal responsibility for protecting the nation’s forests—conducts surveys and research and undertakes reforestation of areas affected by pests. DHS plays a critical role in protecting agricultural interests—including the nation’s forests—by coordinating activities with USDA designed to keep pests out of the country. DHS inspects ships, airplanes, vehicles, cargo, and passengers and their baggage for prohibited agricultural materials that may serve as carriers for pests and disease. USDA conducted agricultural inspections in the past, but the Homeland Security Act of 2002 transferred this function, among others, to DHS. Funding for pest management activities comes through annual appropriations and the Commodity Credit Corporation (CCC), which is a government-owned entity that finances farm commodity, conservation, and trade programs and provides funding for agricultural-related emergencies. The Secretary may transfer funds from the CCC (or other available USDA appropriations) for the arrest, control, eradication, and prevention of the spread of a plant pest and related expenses. State agencies also play an important role in managing invasive species. For example, state agencies impose quarantines to prevent the movement of infested materials within their state and take actions to eradicate pests. Working with APHIS, state agencies also monitor for specific plant pests, including some that have already arrived in the country and others that have not but are believed to pose a threat. In addition, APHIS and the Forest Service enter into cooperative agreements with states to jointly carry out eradication programs and provide funding assistance for these programs. Evidence suggests that the Asian longhorned beetle will be eradicated, while the emerald ash borer and P. ramorum are likely to continue to infest and damage forest ecosystems indefinitely, despite efforts to control them. Asian longhorned beetle: Efforts to eradicate the Asian longhorned beetle appear likely to succeed in New Jersey, New York, and Illinois. Over 8,000 trees infested with the beetle have been removed, and over 600,000 trees have been chemically treated to protect against beetle infestations. As a result of these and other actions, federal and state agencies have been able to reduce the size of the infested areas. APHIS's current goals for Illinois and New Jersey are to confirm eradication and end the management programs in 2008 and 2012, respectively. The current goal for declaring eradication in New York is 2021. Emerald ash borer: In contrast, we reported in April that it is unlikely that the emerald ash borer can be eradicated in the United States. Its small size, inconspicuous habits, and flight capabilities have aided the spread of the borer. In addition, human activities, such as moving infested firewood, have amplified the natural spread of the insect. Current management goals call for eradicating the borer in Indiana and Ohio and containing it in Michigan, which has the most extensive infestations. The pest has killed an estimated 15 million trees. USDA estimated that the cost of removing and replacing dead ash trees in urban and suburban areas could reach $7 billion over a 25-year period. P. ramorum: Similar to the borer, it is unlikely that P. ramorum can be eradicated in the United States. Managing the pathogen is difficult given the size of the infestation and the many ways it can be spread— through movement of plant material, soil on car tires, and possibly even fog. APHIS and state agencies have attempted to eradicate the pathogen from forests in only a few situations where the infestations were relatively small, such as in Curry County, Oregon. While seemingly impossible to eradicate from the natural environment, APHIS and state agencies are hoping to eradicate the pathogen from nurseries to reduce the risk that infected ornamental plants will spread the pathogen to other locations in the country. P. ramorum has killed tens of thousands of trees and led to the destruction of over 1 million nursery plants. These trees and plants were worth millions of dollars in ornamental, timber, wildlife, and environmental value. The success of efforts to eradicate the Asian longhorned beetle, the emerald ash borer, and P. ramorum has been affected by factors relating to species biology, quarantines, detection and control technologies, and funding. Specific biological characteristics of each of the three pests greatly influence the potential success of eradication efforts. The Asian longhorned beetle is a large, conspicuous bug that does not fly far from the core infestation. As a result, it is fairly noticeable and does not spread quickly, making it easier to detect and control. Conversely, the emerald ash borer and P. ramorum are more insidious and can spread over greater distances and more rapidly, making control efforts more difficult. Officials involved with all three pests believe that the use of quarantines has helped to reduce the spread of the pests but we observed that implementing quarantines can be difficult. Quarantines help limit the spread of an invasive species by regulating the movement of potentially infested materials—such as firewood, nursery plants, and wood debris. However, the effectiveness of quarantines is limited by the prevailing knowledge about how the pest spreads and about the extent of its infestation. Since the Asian longhorned beetle infestations were relatively small, identifying the geographic boundaries for quarantines was fairly easy. In contrast, the boundaries for the quarantines for the borer were revised several times in response to information that indicated the infestations were much larger than originally thought. As a result of the incorrect quarantine boundaries, there was a greater risk that people would move infested material to unaffected locations. Similarly, the quarantines for P. ramorum had to be revised after learning that a nursery outside the quarantined area had become infested and had shipped plants to at least 22 states. The success of quarantines can also depend heavily on effectively educating the public about the ways in which pests can be spread. For each of the three forest pest species we reviewed, certain normally harmless actions—such as moving firewood or tracking soil in hiking boots—can result in transporting the pests to new locations. Because nearly any individual can engage in such actions, including residents traveling to campgrounds or vacation homes and small firewood dealers, it is hard to define and reach target audiences with information about quarantines and enforcement efforts. Educating the public about activities that could spread the pests and then enforcing compliance with quarantines are thus daunting tasks. While stakeholders believe that outreach efforts by the three pest management programs have helped educate the public about the dangers of individual actions, all it takes is one piece of infested firewood or contaminated soil to start a potential infestation. Successful control and eradication of the three forest pests we reviewed have been constrained by a lack of cost-effective tools for detecting and eliminating the pests. Detection methods for the three pests consist largely of visual observations, and in the case of P. ramorum, costly laboratory diagnostics.