Fire Ants
The red imported fire ant, a native of southern
Brazil, currently inhabits eleven southern states,
as well as isolated areas in New Mexico and
California. In North Carolina, imported fire ants
are found in 71 of 100 counties, including isolated
areas in western NC. These areas are currently under
quarantine by the U.S. Department of Agriculture and
the North Carolina Department of Agriculture &
Consumer Services (NCDA&CS), regulating the
export of certain items that might carry ant
infestations to other parts of the country.
Infestation Expansion
Even if you are not
currently in a quarantined area, you should be aware
of how fire ants will affect you and how you can
control them because North Carolina’s fire ant
infestation is expanding into counties adjacent to
the quarantine zone. The ants expand naturally and
steadily into new territory because of their high
reproductive rate; mild winter weather has
accelerated their movement. Current technology and
control efforts are not expected to reverse this
growth trend in the foreseeable future. In addition,
long-distance movement often occurs because of human
activities, primarily through the transport of
fire-ant-infested nursery plants and sod into areas
outside of the federal and state quarantine zone.
|
Commercial and Public Impact
 From
an agricultural perspective, red imported
fire ants are nuisances primarily because
they annoy field workers and because their
mounds may damage harvesting equipment.
Livestock injury and crop damage are usually
minor. Fire ants have a much greater impact
on the orna-mental plant, sod, and
landscaping industries because of problems
associated with shipping infested plant
material into uninfested areas of the
country. Mounds discovered in previously
uninfested areas of North Carolina are
frequently traced to landscaping performed
at commercial and residential developments.
For the general public, two aspects of red
imported fire ant infestations are
particularly annoying: the unsightly mounds
formed in lawns and yards and the painful
stings received when mounds are disturbed.
Within 24 hours after a person is stung, a
pustule-like sore forms at each sting site
(as shown here), which usually itches
intensively. Scratching the pustule may
rupture the skin, leading to secondary
infection and scarring. A small proportion
of people stung is highly allergic to fire
ant stings and requires immediate medical
attention. As red imported fire ants spread
into more populated areas of the state, more
people are likely to be stung. Encounters
with fire ants can be expected not only
outdoors but indoors as well. In other
southern states foraging ants have invaded
private residences and buildings such as
offices, hospitals, and nursing homes. In
these situations, fire ant control is more
critical and potentially more difficult
because of concerns related to both the ants
and the indoor use of chemical insecticides.
|
|
Identification
 Adult
red imported fire ants are reddish to dark
brown and occur in five forms: (1) minor
workers, about
1/8
inch long; (2) major workers, about
1/4
inch long; (3) winged males and (4) females,
each about
1/3
inch long; and (5) queens, about
1/3
inch long. Fire ant mounds vary in size but
are usually in direct proportion to the size
of the colony. For example, a mound that is
2 feet in diameter and 18 inches high may
contain about 100,000 workers, several
hundred winged adults, and one queen. If you
break open an active fire ant mound, you
typically find the "brood" - whitish rice
grain-like larvae and pupae. These immature
ants will eventually develop into workers or
winged adults. Mounds constructed in clay
soils are usually symmetrical and
dome-shaped; mounds built in sandy soils
tend to be irregularly shaped. It is often
difficult to distinguish the red imported
fire ant from the tropical fire ant and the
southern fire ant, which are also found in
North Carolina. For positive identification,
take a specimen to your county
Cooperative Extension Center.
Reproduction
During the spring and summer, winged males
and fe-males leave the mound and mate in the
air. After mating, females become queens and
may fly as far as 10 miles from the parent
colony. However, most queens descend to the
ground within much shorter distances. Only a
very small percentage of queens survive
after landing. Most queens are killed by
foraging ants, especially other fire ants.
If a queen survives, she sheds her wings,
burrows into the ground, and lays eggs to
begin a new colony. In the late fall, many
small colonies of fire ants will appear.
Many of the colonies will not survive the
winter unless the weather is mild.
Feeding Habits
Fire ants prefer oily and greasy foods. They
also feed on many other insects and, from
that standpoint, could be considered
beneficial. To find food, workers forage
around their mound often in underground
tunnels that radiate from the mound. If the
mound is disturbed, ants swarm out and sting
the intruder.
|
|
Back |
|
