The Center for Invasive Species Research

CISR: Leading the Fight Against Invasive Species in California


How Many Non-Native Invertebrates Establish Each Year in California?

  • Over the period 1700 to 2010, 1,686 non-native invertebrate species established in California
  • The majority, ~84% (1,416 species) are insects, followed by mites (~8%), and spiders (~3%)
  • Small sucking insects (e.g., aphids, whiteflies, scales, mealybugs) associated with live plants, account for ~28% of established insect species
  • Approximately 44% of non-native invertebrates likely arrived from populations established elsewhere in North America (i.e., other parts of the USA and Canada)
  • From 1970 to 1989, the annual rate of detection of established populations of new invertebrate species in California was ~6 per year
  • From 1990 to 2010, the annual rate increased to ~ 9 per year, a 50% increase
  • Of the new invertebrate species that have established in California ~19% (314 species) are considered pests
  • Invasive species cost California a lot each year. In 2016 this cost was estimated at $6.18 billion.

Read more about Non-Native species in California


Red Alert!
Huanglongbing (HLB) Found in Los Angeles County
Red Alert for Huanglongbing (HLB)In April 2012 the California Department of Food and Agriculture (CDFA) removed a pumelo tree with a lemon graft from Hacienda Heights in Los Angeles County after the tree and an Asian citrus psyllid found on the tree both tested positive for a lethal citrus disease, Huanglongbing (pronounced Wong-Long-Bing [HLB]). HLB is caused by a bacterium, and HLB-causing bacteria kill citrus by affecting the food transportation systems of infected trees. There is no known cure for the disease, and the HLB-bacterium does not pose a threat to humans, pets, or other plants. Continue reading on CISR blog

Red Palm WeevilSpotlight: Red Palm Weevil

The Red Palm Weevil is widely considered the most devastating insect to attack palms has been found in Laguna Beach, Orange County California. The weevil was originally found by a landscape specialist in late August 2010 infesting a Canary Islands palm in a residential area. Subsequent investigation by plant health regulatory officials confirmed the presence of weevils at the original detection site.

Read more about the Red Palm Weevil

New Invasive Species on CISR

Tea Shot Hole BorerPolyphagous Shot Hole Borer

The Polyphagous Shot Hole Borer carries a symbiotic fungus. The beetle can be a serious pest on tea in Sri Lanka and India...

Ficus WhiteflyFicus Whitefly

Ficus Whitefly attacks various Ficus species. Feeding may cause yellowing of leaves, defoliation and branch dieback...

Bed BugsBed Bugs

Bed Bug infestations have been reported from all over the US and Europe, and California is no exception. Together with bat bugs, swallow bugs, and poultry...

Brown Widow SpiderBrown Widow Spider

The Brown Widow Spider does have an hourglass but it is typically an orange shade rather than the vivid red of a black widow. The brown widow looks...


Can Exotic Species Evolve and Become Invasive in their New Home?

Have you ever wondered why only a small fraction of introduced species of plants and animals become invasive while others remain well behaved in their new home? This is a puzzling question for invasion biologists and regulators developing plans to manage invasive species. Dr. Norman Ellstrand , a Professor of Genetics in the Department of Botany and Plant Sciences at UC Riverside has studied this issue. In a new contribution to the CISR website, Norm provides two different ideas for us to think about: (1) some species are “born bad” and they have a natural ability to invade and become pests quickly, while (2) other introduced species that were initially well behaved in their new home for a very long time, perhaps a 100 years or more, under go slow genetic changes as they adapt to their new environment and they evolve to become invasive! You can read about more of these really interesting ideas

FAQ's about Invasive Species

What are invasive species?

Invasive species, alien species, exotic pests, bio-pollution, non-indigenous species, or invasive alien species, are common names that categorize non-native animals, microbes, diseases, or plants that are pests. These pests are not native in areas in which they cause problems and they are considered "invasive" because they invade new areas and the resulting invasion causes economic or environmental problems. Read more invasive species FAQ's

Where do invasive species come from?

Invasive species are often native to a country or area different to that in which they have invaded and are now causing problems. On average, California acquires around six invasive species per year, this is a rate of one new species every 60 days. Hawaii and Florida acquire new species at a round of around 15 per year. Read more invasive species FAQ's

Why are invasive species a problem?

Invasive species cause a wide diversity of economic and environmental problems which almost always arise from uncontrolled population growth and spread in the area which has been invaded. Economic problems arise from the costs required to control invasive species, to reduce their rate of spread, or the need to inspect agricultural products that are being exported that may accidentally move the invasive pest to a new area Read more invasive species FAQ's


More Information

General Campus Information

University of California, Riverside
900 University Ave.
Riverside, CA 92521
Tel: (951) 827-1012

Career OpportunitiesUCR Libraries
Campus StatusDirections to UCR

CISR Information

Center for Invasive Species Research
Chapman Hall, Room 108A

Mark Hoddle
Director of the Center for Invasive Species Research
Tel: (951) 827-4714
E-mail: cisr@ucr.edu