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Serious Economic Consequences Forecast For Infestation of New Fire Ant in California


Serious Economic Consequences Forecast For Infestation of New Fire Ant in California

(May 28, 1999)

The red imported fire ant -- the latest in a line of "exotic" insect pests to establish a toehold in California -- could cost the state's homeowners more than $250 million a year if it makes a permanent home here.

The estimate recently calculated by an entomologist and an economics graduate student at the University of California, Riverside includes the costs of chemical pesticides used to treat infestations in the yard, medical treatment of the aggressive ant's painful sting and repairs for damage caused by the ants to outdoor electrical equipment such as household air conditioners.

The "conservative" estimate is based on the experiences of residents in Arkansas, one of the southern states where the red imported fire ant is firmly established, said Jay Hamilton, who is completing his Ph.D. in economics at UCR. Hamilton worked with John Klotz, a Cooperative Extension urban entomologist at UCR, to gauge the impact of the fire ant on the urban, agricultural and wildlife environments of California. Les Greenberg, a postdoctoral entomologist at UCR, and Karen Jetter of the University of California Agricultural Issues Center also contributed to the study. Hamilton and Klotz presented their findings on May 25 at a Sacramento conference of the Agricultural Issues Center.

"The fire ant is really a triple threat. The agricultural, urban and wildlife areas of California will be impacted," Hamilton said.

In addition to the urban impact, farmers and nursery growers stand to lose from increased costs of production associated with controlling the insects. And, the red imported fire ant is also known to prey on certain wildlife, such as the hatchlings of tortoises and other reptiles, Hamilton said.

Last October, red imported fire ants were discovered in large numbers in Orange County. Since that discovery, more than two dozen other infestations have been identified in that county, which is now under quarantine by the California Department of Food an d Agriculture, restricting the movement of nursery stock until treated and certified free of fire ants. Ants have also been found in San Diego, Los Angeles, Fresno, Riverside, Kern and Stanislaus counties.

The economic impact to the nursery industry could be $1,000 to $2,000 per acre, Hamilton estimates.

The red imported fire ant can infest lawns, school playgrounds, parks, agricultural fields and wild land areas. They are often detected by their dome-shaped mounds up to 18 inches tall, each of which can contain up to a half million ants. They aggressively protect their colonies; in fact, they swarm very rapidly out of their mounds if disturbed. Each ant can sting repeatedly, with the venom causing a painful burning and itching sensation followed by a skin reaction resulting in pustules.

The annual $250 million urban economic impact calculated by Hamilton and Klotz does not include losses to the state's $26 billion agricultural industry. But in agriculture, the insects can attack farm workers, clog irrigation lines, short-circuit electrical systems and damage farm equipment. They can also attack newborn calves and poultry.

The UCR scientists did cite several instances from Texas in which farmers' costs increased due to red imported fire ant infestations:

  • Costs of hay production increased between $2 and $35 an acre, according to various Texas surveys. Included in the costs are damages to mowing equipment by the ants' tall mounds. California's half-million acres of hay is valued at more than $1 billion a year.
  • Texas veterinarians estimate that some $750,000 is spent in that state each year to treat small farm animals and pets attacked by fire ants.
  • Based on the Texas experience, the UCR scientists estimate a one-half percent to 2 percent increase in production costs for such California farm commodities as wine and table grapes, olives, figs, bell peppers and peaches.

"California has many crops not commonly produced in the southeast, so we're not sure of the impact of the red imported fire ant on those commodities," Hamilton said.

The ant also poses a threat to the environment in many coastal and lowland wilderness areas of California, according to Hamilton and Klotz. They decrease a region's biodiversity by displacing native fauna and they can attack ground-nesting birds, they noted.

The red imported fire ant is the latest of California's so-called "exotic" pests, including insects which migrate into the state or hitch a ride on planes, trains, trucks, ships and automobiles carrying produce. It is not known exactly how the fire ant entered the state to cause the current infestation. The insect has been previously intercepted a number of times at border agricultural stations.


The University of California, Riverside (www.ucr.edu) is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 21,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion.

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