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Red Imported Fire
Ant Biology
 The
scientific name of the red imported fire ant is Solenopsis
invicta. It was taxonomically identified by Dr.
William Buren in 1972, he chose invicta specifically
due to its meaning -- invincible. It was earlier identified
as Solenopsis saevissima Forel var. richteri.
However, S. invicta is the name under which
much of the research on this insect pest has been
published.
It is placed in the Solenopsis genus
by its 10 segmented antennae with a 2-segmented club.
It also has a stinger, a 2 segmented pedicel, and
an unarmed propodeum.
Solenopsis invicta's common
name is the red imported fire ant. Like other fire
ants it derives part of its common name from the intense
'fire' sensation felt by a person when they are stung
by it. Its common name differentiates it from the
black imported fire ant.
Life Cycle of the Red Imported
Fire Ant
The general biology of RIFA has been
determined, however, there are numerous aspects of
its biology that are not fully understood.
Queen
The queen is the matriarch of the fire ant colony.
Living upwards of 6 years, her sole work in life is
production of eggs. A fully mature queen can produce
1000 eggs/day. The red imported fire ant species is
different from some ant species in that two distinct
'lines' that have emerged. There are monogyne and
polygyne colonies. That is, there are colonies in
which there is only one queen, and others where multiple
queens are able to survive within a colony. Researchers
have found that in polygyne colonies there is a dominant
queen to which a majority of workers will be attracted.
Co-existing queens are tolerant of each other, but
are competitive on a reproductive level.
Workers/Foragers Workers are sterile
females whose work within and outside of the colony
is mediated by the needs of the queen and the brood.
There are major and minor workers -- they are differentiated
by head capsule width.
A generalized time line for each stage:
- From Egg to Larvae --- 7-14 days
- From Larvae to Pupae --- 12-15 days -- RIFA larva
have four molts prior to pupation
- From Pupae to adult --- approximately 10 days
- From egg to adult it takes 20-45 days --- on average
-- 30 days
General Behavior/Colony Life
There are several behavioral characteristics that
identify this insect pest. One of the characteristics
of RIFA is the type of mound it constructs.
Unlike native ants, RIFA mounds do not have one central
opening into the colony. An extensive tunneling system
is present within the mound.
The network of tunnels inside the mound can convey
sound to the limits of the colony. Sounds somewhat
louder than a whisper have been measured from disturbed
fire ant colonies.
Queen
Although the queen is the matriarch of the colony,
she is not in total control. She is dependent on worker
ants to care and feed her.
Worker/Foragers
The ants which work in a colony have many roles ---
nurse, mound builder, mound defender, and forager.
The age of the ant determines some of its role, and
the size also. Young ants (nurse ants) are found with
the brood. As they age they move into the reserve
stage where they can be found repairing tunnels in
the mound or aggressively defending the mound against
intruders. The oldest ants are generally the foragers.
Brood (pupae, larvae)
Brood, the non-mobile stage of fire ants, are not
entirely without means of communication or behavior.
Although little research has been conducted on this
life stage observations that have been made are quite
insightful. For example, it has been observed that
larva will rock back and forth to draw attention to
themselves so that workers will feed it.
Reproductives
An individual colony enters into a reproductive
stage relative to competition and availability of
food. Reproduction begins with nuptial flights. When
environmental conditions are good (generally after
a rain), workers will create holes in the mounds surface
where male ants leave the nest and form large masses
in the air. The female then leaves the nest and she
flies into this aggregation of males. Male and females
mate in the air. Within a short period of time, the
male is dead. After mating the female --- now a queen
-- then begins the process of starting a new colony.
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