Historically, people have frequently brought species of plants and animals with them from their native lands to California, either accidentally or intentionally. Some introductions did unexpected damage while others had positive outcomes (food and horticultural crops). Many invasive plant problems began as ornamental plants for sale by nurseries and garden centers. Today, exotic and invasive plants are still available in commercial nurseries. Other exotic species arrive in products brought into California by travelers or shipped in commercial trade.
Many exotic invasive pests are of major concern in California. The glassy-winged sharpshooter (an insect) and purple loosestrife (a weed) are two invasive species that are established in some areas but still threaten to invade other areas. Newer exotic species of concern include Diaprepes root weevil, light brown apple moth (LBAM), and various aquatic weeds. Some of the worst invasive plants in California, saltcedar and yellow starthistle, have caused substantial changes to California's wildlands. Insect-carried diseases such as West Nile virus threaten public health and also affect horses and native birds.
What can you do to help stop the spread of exotic and invasive species?
Don't release exotic or invasive plants into the environment. Don't dump your aquatic plants or aquarium water into local waters, since many aquarium plants are highly invasive. Many invasive plant species are still sold at nurseries and garden centers. The California Invasive Plant Council promotes horticultural alternatives to invasive plants in a series of regional brochures entitled Don't Plant a Pest.
Use plants native to your area for landscaping.
Native plants have benefits such as requiring less water, providing habitat for native butterflies and pollinators, and usually have fewer pest problems, too!
Don't bring foreign plant or animal material into California. Be careful what you bring back when you travel, and don't spread species from local quarantine areas to non-infested areas.
Report invasive species in your area! Contact your local UC Cooperative Extension office or Agricultural Commissioner to report invasives and to get information on controlling invasive species on your property.