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Invasives alert archives

The following Invasives Alerts have appeared on our site in the past. Even though we moved these alerts to our archive, the weeds they describe are still active and important. They have been moved to the archive only to highlight newer additions, and to ensure the home page loads quickly.

Note our disclaimer regarding lists of species resources on our web site.

Animal & pathogen invaders

Anoplophora glabripennis (September 2005)
Asian longhorned beetles Anoplophora glabripennis, a known and established pest in the eastern part of North America, has recently been detected in California. This is exceptionally bad news. We have a number of resources to help you look for this pest in your area.
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Cactoblastis cactorum (August 2002)
The cactus moth, Cactoblastis cactorum, known best as a biological control success in places like Australia and South Africa, is now established in North America and the Caribbean where it poses a critical threat to the vast biodiversity of native prickly pear cacti. Information on where it is spreading is critically needed.
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Megabalanus coccopoma (January 2007)
This Pacific barnacle has been detected in the Atlantic Ocean off Brazil, and in the Gulf of Mexico. Now it has been detected in coastal Georgia. The impacts of this barnacle are as yet unknown. You should report any east-coast detections of this barnacle.
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Mytella charruana (September 2006)
This tropical mussel has been found in the Mosquito Lagoon portion of the Indian River Lagoon, Florida. All indications are that this mussel is reproducing---nearly 600 individual mussels have been collected from the lagoon. This mussel could displace natives and adversely affect commercially important oysters. It has now also been found in Georgia!
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Rhinogobius brunneus (September 2006)
A nonnative freshwater goby, tentatively identified as Rhinogobius brunneus, has been found in spawning condition in the state of Washington. Be alert for this species in Pacific Northwest waters!
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Known plant invaders sighted in new areas
These plants are well known wildland area weeds which have been spotted expanding their range, or which are reaching population levels. A tenacious weed from the west coast appearing on the east coast for the first time would be such an example.

Alliaria petiolata (April 2000)
Garlic mustard is no stranger to those who defend wildlands against invasive species. The bad news is that this invader is now appearing in Utah, Colorado, Idaho, and Oregon.
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Brachypodium sylvaticum (February 2002)
Don't take a chance with this grass! It creates monotypic stands in open grassland and forested habitats, and has been rapidly expanding its range in Oregon's Willamette Valley. It could likely spread into Washington, Idaho, and northern California!
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Cenchrus ciliaris (July 2000)
This plant is widely used in Texas and northern Mexico as a pasture grass. Unfortunately it is an invasive grass that is invading wildlands. It is supporting fire in communities that are not fire-adapted. Look for it in arid states like Arizona, New Mexico, Texas, California, and Oklahoma.
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Euonymus alatus (March 2000)
This popular horticultural tree is usually quite well behaved in urban situations but it is a wildland weed in a number of states, including Connecticut, Virginia, Pennsylvania, WI, IL, RI, and OH.
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Oxalis pes-caprae (September 2002)
Don't let this pretty little garden pest get into your natural area...it will rapidly create hundreds of tiny bulblets that are nearly impossible to eradicate! This herb has been recently spotted invading native coastal dunes in northern California, and since it occurs in gardens in both coastal and inland regions, it could potentially spread from these disturbed areas into pastures, native grasslands, and other habitats.
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Glyceria declinata (August 2006)
Possibly easily avoiding detection because it looks like the more widespread invasive Lolium, this grass is showing up in vernal pools throughout California's Central Valley.
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Salvinia molesta (November 1998)
A weed so vile it is illegal to possess in many US states, this rapidly reproducing water fern has been spotted near the Texas-Louisiana border, and is now in the Colorado River. It can have a doubling time of less than a week, so if spotted it must be dealt with immediately.
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Sapium sebiferum (October 1998)
Another riparian problem! Chinese Tallowtree has proven its weedy, reproductive powers in the southeastern USA. It is starting to gain a foothold in California, and could be as bad as Tamarisk or Melaleuca. This tree is widely used in horticulture, and birds help spread the seed.
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Sesbania punicea (October 1998)
Managers in California and other hot climates beware! This attractive, red-flowered shrub in the legume family has been spotted spreading in the Sacramento area. It has already demonstrated its weedy tendencies in Texas, Georgia, and South Africa, and has potential for being a problem in other riparian wetland areas.
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New plant of unknown characters
The following plants have been found, usually in somewhat small populations, growing in wildlands. The threats these plants pose are unresolved--they may be serious invaders, or they may be waifs.

Cayratia japonica (March 2001)
Although this is a plant of unknown properties, a common name like "bushkiller" sounds troublesome! Cayratia is a vine from the grape family that has been observed escaping in Texas and Louisiana, and it may be elsewhere in the Gulf Coast.
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Ceratonia siliqua (April 2001)
Unfortunately, this nice yard tree used extensively in warm areas has an invasive streak. It has been observed escaping from cultivation. Indeed, it is considered one of the worst weeds at the University of California, Riverside Botanic Gardens.
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Coincya monensis (January 2000)
This mustard-family plant has started to establish itself in sandy dunelands of California. Managers in the northern Pacific coast, beware!
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Cryptocoryne beckettii (March 2001)
This popular and commonly grown aquarium plant has been spotted invading natural areas in Texas. It may not be a rapidly growing pest like some exotics, but it has been seen making monocultures and excluding native biodiversity.
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Glyceria maxima (July 2000)
This invader of Canadian and Australian/New Zealander wetlands was spotted twice in Wisconsin in the 1970s. But recently it showed up in Massachusetts. Keep your eyes open for this wetland invader.
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Hypericum canariense (November 2001)
This pretty shrub is occasionally planted as an ornamental, and has been spotted escaping in several sites in coastal California. It is a wildland invader in Hawaii, and current populations, especially in San Mateo County, are spreading rapidly.
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Ononis alopecuroides (December 1999)
This legume has been spotted escaping in California. It produces large numbers of seeds and has potential to spread rapidly.
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Phellodendron amurense (April 2000)
This landscape tree, although somewhat weak in cultivation, is making itself at home in wildland forests in New York and Pennsylvania. It is unclear if this plant will become a tough foe, or if it will be easily controlled. Seed production is high!
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Romulea rosea (March 2001)
A very pretty little plant in the Iris family, this species from South Africa is popping up along trails in California. We do not know if this plant will be much of a wildland offender, but it is worth keeping an eye on.
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Schinus polygamus (July 2000)
The weedy genus Schinus has another species we might have to worry about. While Schinus polygamus is perhaps not quite as weedy as its sibling species, it may cause trouble in moist, warm areas. Present records have it in California.
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Tribolium obliterum (April 2001)
This grass has been discovered in North America for the first time. Infesting a site in Fort Ord, near Monterey California, we do not know what kind of threat this plant will pose. It occurs as a wildland invader in other countries, but it does not seem to form rapidly expanding populations.
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Ventenata dubia (January 2000)
This grass has been spotted in small populations in a number of states. It is starting to increase its range. It looks like a combination of Avena and Bromus!
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Other site resources

Listserves, meetings, and news focused on invasive species issues.
Photography archive
One of the largest collections of photographs of invasive species (mostly plants) available on the web.
Gallery of pests
A rogue's gallery of many of the invasive pests and pathogens that have invaded North America, or that have the potential to do so.

Updated October 2006
©The Nature Conservancy, 2005