It can be very difficult to accurately assess the economic costs of invasive species. Below we present some estimates that have been published. If you have a favorite factoid, email it to John Randall [jrandall(at)tnc.org], but please make sure you include an appropriate citation for the information.

Mexico/national impacts

Cactus moth (Cactoblastis cactorum) in Mexico could threaten $80 million annual industry on cactus, a source of food for humans and livestock.
See: Zimmermann, H., and Cuen, M.P.S. 2006. The consequences of introducing the Cactus moth (Cactoblastis cactorum) to the Caribbean, and beyond. (www.cactoblastis.org)

USA/national impacts

The annual losses to the Great Lakes Region, because of ship-borne invasive species, is at least $200 million.
Lodge, D., and Finnof, D. 2008. Annual Losses to Great Lakes Region by Ship-borne Invasive Species at least $200 Million. Great Lakes United (www.glu.org).

African lovegrass (Eragrostis plana) destroyed the pasture value of 10% of southern grazing lands and severely damaged the area's cattle industry. Annual losses are calculated at $30 million per year.
See: Rosa, F., Ramos, J.V., and Ziller, S. 2007. Economic impacts of Eragrostis plana on the Southern Brazil grasslands. Biological Invasions (in prep.).

Leafy spurge (Euphorbia esula) costs ranchers in ND, SD, MT, WY more than $144 million a year.
See: Bangsund, D.A., and Leistritz, F.L. 1991. Economic impacts of leafy spurge on grazing lands in the northern Great Plains. NDSU Agriculture Economic Report No. 275-S.

The annual US cost from invasives is $120 billion, with over 100 million acres being affected (i.e. the size of California).
See: Pimentel, D., Zuniga, R., and Morrison, D. 2005. Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological Economics. 52: 273-288.

Global impacts

The estimated damage from invasive species worldwide totals more than $1.4 trillion--five percent of the global economy.
See: Pimentel, D., McNair, S., Janecka, J., Wightman, J., Simmonds, C., O'Connell, C., Wong, E., Russel, L., Zern, J., Aquino, T. and Tsomondo, T. 2001. Economic and environmental threats of alien plant, animal, and microbe invasions. Agriculture, Ecosystems and Environment 84: 1-20

Efforts to control purple loosestrife (Lythrum salicaria) cost $45 million per year.
See: Pimentel, D., Lach, L., Zuniga, R., and Morrison, D. 2000. Environmental and economic costs of nonindigenous species in the United States. Bioscience 50: 53-65.

Learn more!

If you like to crunch numbers, here are some economic statements and press releases from Dr. David Lodge, University of Notre Dame:
A fact sheet on invasives and costs in the US Great Lakes Region

Q &A clinic
The most frequently asked questions answered for your edification.

The worst weeds
Learn about an invasive plant species in your neighborhood that threatens native biodiversity.

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Here we have PowerPoint presentations on invasive species. Web slideshow versions are also on line if you do not want to download the PowerPoint files.

Learn even more
People who talk about invasive species often present facts without citing their sources. Are you curious about our sources? Here they are for you!

How you can help
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Red Alerts!
Species which are either new to an area, or are showing alarming symptoms such as signs of signicant, new expansion.

Conservation stories
Read about how different people have had great successes dealing with invasive species.

Tool reviews
Read our reviews of hardware that are useful for those working in invasive species management.

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How you can contact the core staff of The Nature Conservancy's Global Invasive Species Team.