Red Imported Fire Ant Information
Background
The red imported fire ant (RIFA) is a nuisance, and its sting
can cause medical problems. Fire ants can interfere with outdoor
activities and harm wildlife. And mounds are unsightly and may
reduce land values.
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.
To view the historical progression of the Red Imported Fire Ant,
click HERE.
Where They Infest
Fire ants commonly infest lawns, school yards, athletic fields,
golf courses and parks. In these places, they pose a medical threat
to people and animals. Their mounds also detract from the aesthetic
value of the land-scape.
 Homes
and Building – Fire ants form colonies close to
homes and other buildings 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 are a nuisance and can
threaten sleeping or bed-ridden individuals and pets.
Home Gardens – 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.
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.
Compost Piles, Mulched Flower Beds, Pavement Cracks,
etc. – Fire ants invade compost piles and mulched
flower beds seeking warmth and moisture. 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.
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 tunnel down to the ground water table
many feet below the ground.
Fire Ant Biology
Red imported fire ant colonies consist of the brood (eggs, larvae
and pupae) and several types of adults:
- Winged males (distinguished from the females by their smaller
heads and black bodies);
- Red-brown winged females;
- One or more queens (wingless, mated females); and
- Workers
For a bilogical description of the red imported fire ant, click
HERE.
Worker ants are wingless, sterile females. They protect the queen
by defending the nest from intruders, by feeding the queen only
food the workers have eaten first, and by moving the queen from
danger. They also forage and care for the brood.
 The
winged ants – or reproductives – live in the mound until
their mating flight, which usually occurs in the afternoon, soon
after a rainy period. Mating flights are most common in the spring
and fall. Males die soon after mating, while the fertilized queen
alights to find 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.
A newly-mated queen lays about a dozen eggs. When they hatch
7 to 10 days later, the larvae are fed by the queen. Later on,
a queen fed by worker ants can lay up to 800 eggs per day. Larvae
develop in 6 to 10 days, and then pupate. Adults emerge from the
pupae in 9 to 15 days.
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 ants build mounds in almost any type of soil, but prefer
open, sunny areas such as pastures, parks, lawns, meadows and
cultivated fields. 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.
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.
To learn the differences between common ants and the red imported
fire ant, click HERE.
Medical Problems
Fire ants are aggressive and will defensively attack anything
that disturbs them. They can sting repeatedly. After firmly grasping
the skin with its jaws, the fire ant arches its back as it inserts
its rear-end stinger into the flesh, injecting venom from the
poison sac. It then typically inflicts an average of seven to
eight stings in a circular pattern. Fire ant venom is unique because
of the high concentration of toxins which are responsible for
the burning characteristic of such stings.
Symptoms of a sting include burning and itching, which usually
subsides within 60 minutes. This is followed by the formation
of a small blister at the site of each sting, within the next
four hours. And, 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 and may leave permanent scars. 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, serious swelling 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.
Avoiding Medical Problems – Tips for avoiding
medical problems 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
- Teach children 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.
This fact sheet was prepared
by the
California Department of
Food and Agriculture,
with supplemental information provided by the
Texas Agricultural Extension Service.
For more information on the
Red Imported Fire Ant,
visit CDFA's website at www.cdfa.ca.gov,
or call CDFA Public Affairs at 916-654-0462.
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