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Imported Fire Ants

Published on: 2/5/2014 2:52 PM
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In California, the imported fire ant has infested parts of Orange County. The California Department of Food and Agriculture has an excellent site on the current infestation in our state including identification, quarantine information and facts in English and Spanish.  Fire ant biology and control web pages on the Mississippi State University Extension Services has an excellent site on fire ant biology and control.  University of Minnesota's National IPM Network web site on fire ants is also very informative.

To learn more about the fire ant in California, the following information is from the California Department of Food and Agriculture website (www.cdfa.ca.gov):

Background

  • The Red Imported Fire Ant (RIFA) has recently been found in California. Known for its aggressive behavior, this ant can interfere with outdoor activities and harm native wildlife.
  • Fire ant mounds are unsightly, detract from the aesthetic value of home landscaping and may reduce land values.
  • The RIFA can be a nuisance, and can threaten those who may knowingly or unknowingly disturb their colony.
  • The ants are an established pest in 11 southeastern states, including: Texas, Louisiana, Mississippi, Alabama, Florida, Georgia, South Carolina, and adjacent regions in North Carolina, Arkansas, Tennessee and Oklahoma.

 Where They Infest

  • The ants build mounds in almost any type of soil, but prefer open, sunny areas such as pastures, parks, lawns, meadows and cultivated fields.
  • Homes and Buildings – Fire ants form colonies close to homes and other buildings. They sometimes forage indoors for food and moisture, particularly during the hot, dry summer months. Entire colonies occasionally nest in wall voids or rafters, sometimes moving into buildings during floods.
  • They also nest under cracked pavement, removing dirt from underneath sidewalks and roadways and aggravating structural problems. Colonies in these sites may be difficult to locate.
  • Home Gardens – The ants occasionally feed on vegetable plants in home gardens. The worst damage usually occurs during hot, dry weather. Ants may also be a nuisance to gardeners during weeding and harvesting. Fire ants invade compost piles and mulched flower beds seeking warmth and moisture.
  • Electrical Equipment and Utility Housings – Like many other ants, fire ants frequently infest electrical equipment. They chew on insulation and can cause short circuits or interfere with switching mechanisms.
  • Air conditioners, traffic signal boxes, and other devices can be damaged. Fire ants also nest in housings around electrical and utility units. The ants move soil into these structures, which causes shorting and other mechanical problems.
  • Around Bodies of Water – Fire ants require water to survive and are often found near creeks, run-off ditches, streams, rivers, ponds, lakes and other bodies of water. If surface water is unavailable, they may tunnel down to the ground water table many feet below ground.

 Fire Ant Biology

  • Fire ant mounds can reach 18 inches in height, depending upon the type of soil. Often mounds are located in rotting logs, and around stumps and trees. Colonies can also be found in or under buildings.
  • The average colony contains 100,000 to 500,000 workers and up to several hundred winged ants and queens.
  • Queen ants can live seven years or more, while worker ants generally live about five weeks, although they can survive much longer.
  • The winged ants live in the mound until their mating flight, which usually occurs in the afternoon, following a rainy period. Mating flights are most common in the spring and fall.
  • Males die soon after mating, while the fertilized queen begins looking for a suitable nesting site, sheds her wings, and begins digging a chamber in which to start a new colony. Sometimes several queens can be found in a single nesting site.
  • Colonies frequently migrate from one site to another. The queen needs only about six workers to start a new colony. They can develop a new mound, several hundred feet away from their previous location, almost overnight.

 

What Can You Do?

  • Report any suspected fire ant mounds to your County Agricultural Commissioner’s Office ( listed in the telephone book under the County Government section). Educate children about the fire ant and its potential hazards. Do not enclose or tie pets near the fire ant mounds. Individual ant mounds can be destroyed by pouring one to two gallons of hot tap water into the mound. If enough hot water reaches the queen, it will destroy her and eventually the colony. Hot water treatments are not 100% effective. Other materials used to combat the fire ant can be obtained from your local nurseries or gardening supply store. Some commercially available fire ant combatants are applied as a liquid drench over the mound or as granule baits containing insect growth regulators. Work with your neighbors to schedule fire ant abatements. Destroying mounds on your property will not prevent re-infestation from surrounding properties that are not treated. To stop the spread of these ants, avoid moving soil, potted plants from your property. Fire ants may also be present in firewood stacks, lumber, tires and many other items that may be stored on your property. Any item infested with these ants should not be moved to other areas.

 

Health Concerns

  • Fire ants are aggressive and will repeatedly sting anything that disturbs them. Symptoms of a sting include burning and itching, which usually subsides within 60 minutes. Within the next four hours, a small blister forms at the site of each sting. A white pustule forms in a day or two. Treatment is aimed at preventing secondary bacterial infection, which may occur if the pustule is scratched or broken. Although the stings are not usually life threatening, they are easily infected.
  • On rare occasions, anaphylaxis – or a generalized, systemic allergic reaction to the fire ant stings – can occur, and may be life-threatening. It usually occurs in persons sensitized by a previous sting. It may be manifested by flushing, general hives, swelling of the face, eyes, or throat, chest pains, nausea, severe sweating, loss of breath or slurred speech. If this occurs, the person should immediately seek emergency medical assistance.
  • Treatment – Elevate the extremity and apply ice or a cold compress to reduce swelling and relieve pain. Clean blisters with soap and water to prevent secondary infection. Do not break the blister. Topical steroid ointments and oral antihistamines may relieve the itching associated with these reactions. Treatment with antihistamines and oral steroids may be useful in severe cases.
  • Tips to avoid fire ant stings include:
  • Fire-ant allergic patients should wear closed-toed shoes, socks, and gloves when gardening, and take other precautions to avoid stings; Fire ant mounds near the home should be identified and treated with an ant bait insecticide; and Children should be taught about fire ants and their hazard.
  • These preventive measures should help reduce the health hazards caused by fire ant stings. Your allergist can provide you with more information on fire ant stings.