Ants, Armadillos, and Phorid Flies -
Answers to Frequently Asked Questions*
Selected by the sciLINKS
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Association. Copyright 2001.
Brackenridge Field Laboratory
The University of Texas at Austin
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What is the correct scientific name for the red imported fire ant
(RIFA)? Solenopsis invicta or Solenopsis wagneri
of 1995, the correct name for the red imported fire ant was Solenopsis
wagneri. This change is based on the discovery that wagneri
was the first name given to the species by a taxonomist (a second
taxonomist found this out by sorting through dead ant specimens
in museums and discovered that the same ant species had actually
been named twice). So the first taxonomist assigned the name S.
invicta to this species without having done his homework. By
international rules of nomenclature, the earlier name has priority.
most cases it is usually non-controversial to simply change the
name and inform all the academic researchers about the new, correct
name. However, this is not such a simple case. Many fire ant biologists
believe that because thousands of research publications are referenced
by the name "invicta" that common sense and practicality should
override technically correct taxonomy. There is a procedure for
appealing such bothersome name changes and an appeal is in progress
for S. invicta. Also aesthetically, invicta seems the better
of the two names. The name "invicta" conjures up "invader," "invincible,"
"vindictive," and sounds more poetic in songs than "wagneri." A
case in point: the lyrics of "Queen
Invicta" by environmental troubador, Bill Oliver. Ant
taxonomists are not pleased that the change from invicta to wagneri
was overturned. The name "invicta" is as difficult to
extinguish as the species to which it refers!
How, when, and why were fire ants imported to the U.S. and where
do they occur at the moment?
of all, several kinds of fire ants are native to Texas. When people
ask this question, they really mean imported fire ant species. Apparently
the introductions of pest fire ants were accidental. Perhaps the
soil of potted plants or ballast on ships arriving from South America
to Mobile, Alabama contained invicta nests. Exactly when
is not certain. There were invasions by two pest fire ant species.
The first, the black imported fire ant from Argentina (S. richteri),
was barely established and spreading when the red imported fire
ant (S. invicta) arrived and proceeded to shove aside its
cousin (which now survives in Mississippi and western Georgia).
The original arrivals were probably in the 1920s or before. Professor
E.O. Wilson, the famous ant biologist at Harvard, was first to discover
the invasion while he was still a budding high school entomologist
in Alabama. See the most recent USDA
distribution map (248k) by county and time of arrival.
you live in the northern U.S. where the ground freezes and you think
you might have fire ants, check with a nearby university with a
department of entomology. Though fire ants probably will not survive
winters in northern states, these ants may have been accidently
introduced in potted plants and set up temporary residence during
warmer months. Fire ants will locate mounds near heat sources (steam
pipes, concrete walls, etc.) and conceivably could survive in colder
areas than we expect. With
global warming we can anticipate a northward shirt in fire ant populations
across the landscape.
have recently been accidentally exported to Queensland, Australia
and are following a spread similar to that encountered in the U.S.
I'm not sure I have fire ants. How can I be sure?
at the ants. Fire
ants include many opportunistic ant species of the genus Solenopsis.
There are native and imported species. Native Texas fire ants are
very similar to the imported pest, but actually help retard the
spread of the imported species and should be spared if possible.
Both native and imported fire ants are small, dark orange/brown
ants with workers of various sizes that quickly mobilize and sting
en mass when their mound is disturbed . Other than the much
larger "red harvester" or "Texas red ant" which has no variation
in worker size and is conspicuous on its trails and around it's
flat open mound entrance, most other stinging, ground-dwelling ants
in Texas are encountered as solitary individuals. ( right:
native, large worker)
at the nests. Fire ants live and do most of their foraging for food
through underground tunnels. A nest consists of a network of tunnels
and chambers that occupy a vertical column 12-18" in diameter and
approximately 36" deep. After cool, rainy, weather in Spring and
Fall, the ants clear blocked tunnels and expand chambers to create
a conspicuous mound of loose soil above the nest. The colony dwells
in this above ground extension when the temperature there is optimal
for brood development. Though above-ground mounds harden and persist
in some soil types, their absence does not mean fire ants are not
present or receding. (right: imported, large
probably have imported fire ants if the following characteristics
of the ants and their mounds are observed:
not all fire ants are the pest species, distinguishing native from
imported is an important first step before proceeding with chemical
of loose soil, resembling gopher diggings, are found above ground.
are generally numerous and conspicuous.
ants are dark, small, highly variable in size, aggressive, and
have the same body proportions from the tiniest to the largest.
Head width never exceeds the abdomen width, even in the largest
workers. (See sidebar to left and illustration on web site http://uts.cc.utexas.edu/~gilbert/research/fireants/gemvsinv.html).
Which fire ants are the native species and how can I identify them?
the Nexican border of Texas and in West Texas, there exist native
fire ants that are difficult to distinguish from their imported cousins.
However, if you can see four tiny teeth on the mandible or jaw of
a fire ants, it is S. invicta. Native species possess three
Over East, Central and much of South Texas, the most common native
fire ant, S. geminata, can be distinguished without examination
of tiny details of anatomy. First disturb a mound by digging, then
watch for the largest workers. If the heads of the largest workers
are conspicuously wider than the gaster (abdominal segments), you
are looking at the native species.
S. invicta (left) versus S. geminata (right)
We have large red ants that come out of a hole surrounded by open
ground covered in small pebbles. Their sting really hurts! Are these
you have described the Texas red harvester ant, also known as the
Texas red ant or "pogo" (genus Pogonomyrmex). These industrious
ants collect grass seeds and store them in underground granaries.
In fact, they have been shown to reduce rodent numbers by competing
with them for grass seeds. Pogos are eaten by "horny toads" and
are so conspicuous that people usually notice them before getting
stung. Fire ants tend to eliminate this native Texan.
Do fire ants have anything to do with the disappearance of horny
is another question on the minds of people who, as kids, enjoyed
watching these great lizards and now lament their absence. The answer
is either "probably yes" or "definitely no" depending on where you
are. Horned lizards have definitely disappeared over most of the
range now dominated by the red imported fire ant (RIFA). There might
be other species of lizards or snakes that have suffered due to
the presence of the RIFA, but the loss of the Texas Christian University
mascot has certainly been the most conspicuous one. In any case,
the disappearance of horny toads in RIFA areas is probably due partly
to the direct killing of the young lizard by foraging fire ants
and partly to the fact that horny toad food, such as Texas harvester
ants, have been decimated by the RIFA. However, horned lizards have
also disappeared in many areas outside the range of RIFA. It is
probable that the RIFA could still be at least indirectly responsible
for the horned lizard demise even where the RIFA does not occur.
For instance, the publicity about the RIFA has encouraged overuse
of and proliferation of ant baits and poisons, killing all species
of native ants they touch as well as the RIFA. Many people erroneously
assume that the Texas red ant is the imported fire ant and unnecessarily
treat their properties. Aside from thereby causing the demise of
horned lizard, they are also removing dozens of native, friendly
ants and increasing the opportunity for invasion by RIFA into a
vulnerable system with lowered resistance. Agricultural activities
such as shredding and other habitat destruction that prevent weeds
from producing seed also can rob the Texas red harvester ant of
its food source. No seeds = no ants = no lizards.
Why are imported fire ants such a pest, while the native Texas fire
ants are not?
biological wisdom and recent research indicate that fire ants, like
other opportunistic organisms, become more "weedlike" and achieve
pest status when introduced into regions free of their natural biological
enemies, such as parasites and pathogens. A case in point is the
fire ant species native to Texas. Our native fire ant species is
a is a minor nuisance at home, but a major pest in India where it
was inadvertently introduced. Likewise, the pest fire ant from Brazil
is "just another ant" there and not a serious pest. Still, the Brazilian
name for the ant, "lava pé" (translated "wash feet") reflects
its status as a nuisance to those not watching where they stand.
I poured a solution of grits and water on my fire ant mounds. Several
weeks later they were gone. Why not do research on this?
of revenge, desperation, or a hope for quick profits, countless
remedies have been used in attempts to eradicate fire ants. Encouraging
a few fire ant colonies to abandon mounds in a yard is relatively
easy. Even regular watering can cause a colony to move. However,
safely and economically eliminating hundreds or thousands of RIFA
colonies from parks, farms, and ranches has proved to be nearly
impossible. Remedies against fire ants which are effective in a
backyard will not solve the overall problem across the countryside
because no effective and safe measure has proved to be economically
feasible or sustainable on the grander scale.
decisions on what research topics to explore are based on 1) systematic
analysis of past research into the biology of fire ants and 2) an
assessment of the economic and ecological consequences of various
approaches. Qualified scientific personnel and/or the time they
have available is a very limited resource for effective fire ant
research. Therefore it is not possible or desirable to pursue every
line of research suggested at the expense of carefully considered
and ongoing investigations.
Are imported fire ants problem pests in their homelands, Brazil
ants of the species S. invicta and its closely-related species
of ants are not generally viewed as important pests in Brazil and
Argentina. Occasional local outbreaks, which could result from temporary
escape from normal controls due to habitat disruptions, have been
reported in recently settled towns in the Amazon region. It is safe
to say that fire ants native to South America are no more pests
there than are native fire ants pests in North America.
How can I avoid being stung by fire ants?
aware of your surroundings at all times is the way to avoid everything
from car wrecks to rattlesnake bites. If fire ants do crawl onto
your skin, they first bite with their mandibles in order to anchor
for the thrust of the sting. As soon as you feel this pinching sensation,
quickly sweep the ants off before they actually sting and you can
avoid most of the damage! If you must work in proximity to fire
ants, wear rubber boots and gloves powdered with talc.
How do fire ants affect quail and other wildlife?
might have seen pictures of massed fire ants killing hatchling quail
chicks or stinging the noses and eyes of newborn deer. Without question
RIFA can kill young birds, small mammals, and reptiles. However,
in the case of quail, it could be that a more important impact on
populations is the removal of insect food that would normally be
available to quail chicks. Because quail populations fluctuate widely
due to climatic changes, it is hard to pinpoint the extent to which
RIFA might trigger populatioin-wide collapse. Certainly if climatic
conditions are unfavorable, the depredations by fire ants could
become a major factor in affecting the survival of certain species
Why do we find piles of dead fire ants?
fire ants die, workers remove the bodies and body parts from nests.
Nest hygiene is a key to disease prevention in social insects such
as bees and ants. Trash piles, called middens, accumulate in underground
chambers during weather that inhibits above-ground activity, and
are then moved to the surface after spring and summer rains when
ants rebuild galleries and clean house. Midden piles might increase
in size and conspicuousness after a colony has had a territorial
dispute with another colony of ants, after application of pesticides,
or when a colony is experiencing higher rates of disease or parasitism.
We suspect that phorid fly infected ant heads are tossed into these
middens so that the first view of the world by a newly emerged adult
phorid would resemble the garbage dump in Star Wars!
What are the safest and most effective chemical controls for fire
ants in yards and pastures? I don't want to expose
my family and pets to dangerous chemicals.
put small pieces of hot dog as bait around the yard. Visually
match up ants that come to bait with fire ants that you see by disturbing
the mounds. If you have an area dominated by ants other than fire
ants, avoid treating that. If you do have fire ants, use Amdro,
Award, Logic or similar granule bait preparations. These don't
kill instantly but give the workers a chance to take the bait back
to the mound as food where its pesticides disrupt reproduction by
hormonal control over queen ants. Fire ants forage out of underground
tunnels that lead all around within 100' of a mound. Therefore
use a broadcast spreader to evenly distribute the bait over your
a mild day on which you first determine that the ants will swarm
a piece of hot dog. That means they will efficiently harvest
the bait. Broadcast these granules all over the infested area on
a nice day so that the fire ants get all of the bait. The worker
ants will take the granules into the mound. Be patient because these
baits take about 6 weeks to take effect; the mound will die. You
should have control for many months and additional spot applications
of the granule baits when you see small mounds restarting should
keep things tolerable (or with just a mound or two, boiling water
poured on the mound when it comes up after a rain is very effective).
you coordinate with neighbors and use the same treatment area-wide
on the same week, you will reduce the rate of re-invasion.
We find that native ants increase after such treatments and that's
good because they serve useful functions including helping to resist
fire ant invasion. Imported fire ants are often the worst
where native ants have been disrupted by soil disturbances that
accompany home and road construction, or exterminated by broad spectrum
the suggestion: 3/4 lb. hydramethylnon in baited granules
(under trade names "Amdro" or "Siege")
mixed with 3/4 lb s-methoprene in baited granules (under trade
name "Extinguish") broadcast applied per acre. A report
published on trials with this mix is on the web: Amdro/Siege, a
metabolic inhibitor, takes 3-6 weeks after ants consume it to show
an effect and the effect lasts for several months until a re-invasion
occurs. Extinguish is a growth regulator that takes longer
to show an impact, but then can last a year or more. Since
these things are not instantly toxic, workers can distribute each
of them throughout the colony long before effects set in. While
these compounds or breakdown products definitely would not
be good for frogs or fish, if application occurs during a period
when no run-off rains are anticipated, all of the active material
will be taken into fire ant mounds within 30 minutes. Persistence
in the environment is relatively short for both.
answers to this question change frequently. Consult the TAMU extension
service web site at http://fireant.tamu.edu/.
Why not bring back Mirex?
those who don't know about Mirex, it was in many ways a highly effective
product that, when mixed with ant bait and applied aerially, reduced
fire ant populations. The problem was that it was not specific and
therefore killed other ants and insects that consumed the bait.
Mirex is thought to have helped spread fire ants even faster by
wiping out pockets of native ant resistance to the RIFA invasion.
It also produced a toxic and persistent byproduct, dioxin, which
accumulated in ecological systems. Chemical treatments for fire
ants today are much more specific to the target pest, but they are
not perfect. Therefore, it is necessary to identify the ant species,
and whether treatment is even warranted.
What should I do if I have native ants in my yard?
you still have native ants, keep doing what you have been doing
(or not doing). If you see an invading fire ant mound in an otherwise
RIFA-free area, verify that it is not the native species before
attempting to kill it. If you do treat such a RIFA mound, be sure
to confine treatment to that mound or its immediate surroundings.
Armadillos eat fire ants and some people think this might control
the RIFA. Is this a real possibility for controlling the RIFA?
observant folks notice that armadillos dig into fire ant mounds
and correctly assume that they are eating the ants. Armadillos also
dig into mounds in droughts when more favored foods are hard to
find. Actually they do this when the colony inhabits the uppermost
parts of the mound, the portion of the approximate 3 ft deep nest
that offers the best temperature for developing brood. Developing
brood is what armadillos eat. So yes, armadillos probably do have
an effect on fire ants in Texas as well as in in Brazil, where they
are also found. Research should be carried out to assess the effect
predation by armadillos has by comparing fire ant densities in areas
with and without them. However, if armadillos alone could stem the
tide of RIFA, these ants would not have become a problem. Actually,
since some phorid flies attack fire ants when mounds are disturbed,
armadillos and phorid flies could be a winning combination. Until
we examine that idea more carefully, we should all avoid running
over these little fire ant munchers.
Why not import anteaters?
anteaters are terrific ant predators, their cousin, the armadillo,
is already in Texas, but has had little effect on RIFA populations.
Good biocontrol agents are 1) highly host specific, 2) limited by
their host availability, and 3) able to survive in the climate where
they are introduced to control the pest species.
consume a wide range of ants, not just fire ants and, except for
the giant anteater, live in trees and usually eat ants that nest
in trees. Because the RIFA does not usually inhabit trees, the anteater
wouldn't have much of a chance to eat RIFAs. Also, anteaters are
tropical and would not survive cold weather as well as fire ants
do. Importing anteaters as biocontrol agents of the RIFA is an idea
based on comic strips, not scientific observations.
What do phorid flies do to fire ants?
phorid flies are attracted to fire ants swarming over a disturbed
mound or foraging along a trail to food. They hover over ants looking
for a preferred individual. (Each phorid species has a particular
size range of fire ant workers which it prefers.) When the hapless
victim is chosen, the phorid darts in, injects an egg into the ant's
body, and explodes away at warp speed. The attack takes a fraction
of a second and leaves the ant partly paralyzed and disoriented
for a minute or so before she staggers off to join her sisters!
(right: last abdominal segment of phorid with
"harpoon" ovipositor extended) The stinger is a modified
egg-laying device. That's why males of ants, wasps, and bees
injected egg develops in the ant's thorax until after about ten
days the ant dies as the larva moves into the ant's head. The head
falls off and the larva eventually pupates in the safety of the
hard chitin shell that once housed the ant's jaw muscles and brain.
Ant pieces are tossed on ant trash piles or middens and adult flies
emerge from pupae about 45 days after the original attack. That's
the direct effect of mortality that these decapitating flies impose
other thing that phorids "do" to ants is probably the most significant
from the standpoint of biocontrol. As phorids fly above ants looking
for victims, the ants respond by hiding, pilling on top of one another,
retreating into the nest, and posturing in various odd ways. This
fly harassment disrupts the economy of provisioning the nest with
food and protecting home and territory. Native ant species can then
take advantage of the RIFA's distraction and reclaim lost territory.
This more indirect and subtle effect has only recently been identified
as the mechanism by which phorids might reduce the impact of fire
ants. The idea was posed originally by a UT graduate student, Don
Feener, in the late 1970s. At Brackenridge Field Laboratory, he
observed phorids that attacked one of our native ants. Dr. Feener,
now a professor, continues important studies of phorids at the University
Why don't you just release the phorid flies now?
phorid flies are being released in selected experimental sites,
the ant populations of which were assessed before release so that
comparisons can be made post-release. Currently, there are too few
phorids being bred in research laboratories to provide enough for
mass releases in more than a few carefully-selected areas. But even
if there were enough phorids to "go around," only two species, Pseudacteon
tricuspis and P. curvatus, arecurrently available in
substantial numbers. Further research is required to assess the
most effective methods for breeding and releasing up to 15 additional
phorid species, some of which could be more effective than the ones
Now that phorid flies are being released, when will they eradicate
the answer is never. Imported fire ants are now permanent residents
in the U.S. Eradication is possible from pesticides only temporarily
and only at a local scale, but not at a regional level. However,
we can hope for eradication of the pest status of the ant,
assuming that we can find and successfully introduce effective biological
control agents. Even assuming the best results with phorids, it
could take years to reverse seven decades of spread and growth of
RIFA populations. Although we expect phorids to be detrimental to
populations of the RIFA, don't overreact to the media hype about
phorids and expect an overnight solution.
My property is available for this project. Why don't you release
phorid flies on my back yard, farm, ranch?
addition to those considerations, this experimental release/research
phase is limited by availability of flies and researchers. Our laboratory's
procedure is to conduct initial release experiments in areas where
extensive previous baseline data on the ant fauna and its boundary
with imported fire ants has been studied. The good news is that
naturalized phorids have now been documented to have spread up to
15 miles from release sites in Texas, and in Central Texas occupy
more than 100,000 acres (est.).
How big are phorid flies? Will they be a nuisance too?
phorid flies that attack fire ants are tiny. Compare the end of
Lincoln's nose and top of his lip on a U.S. penny to the length
of this Pseudacteon phorid which attacks S. invicta.
Only fire ants and a few dedicated biologists are likely to see
phorids in action. They are not attracted to people as are some
small flies, like gnats and mosquitoes.
species of phorid flies that attack fire ants are specialists; some
even attack only single species of fire ants. For example, our native
Texas fire ants have their own phorid fly and it will not attack
the imported fire ant - that's why we have to bring the specific
phorid fly that attacks the imported fire ant from the countries
from which they were imported.
are over 20,000 species of phorid flies. Most
phorid flies are scavengers and some utilize corpses and are useful
in forensics (the so-called coffin flies). Phorids that show up
in houses typically breed in the sludge in sink drains but could
be coming up from animal remains under the house (e.g. dead rats).
that parasitize ants are a highly specialized minority that do nothing
except attack and consume ants. The vast majority of people will
never knowingly see one of these inconspicuous creatures.
What are the possible negative effects of phorid flies introduced
to control imported fire ants? What will they eat after they kill
off all the fire ants?
Phorid flies of the genus Pseudacteon permitted for release
have been through careful screening to identify those species most
specific to the imported pest fire ant. Prior to the decision to
release target-specific phorids, USDA APHIS produced an Environmental
Assessment (EA) http://uts.cc.utexas.edu/~gilbert/research/fireants/envassess.html.
This document contains a review of the biological qualities in fire
ant-attacking phorids and assesses the potential benefits vs costs
of releasing these exotic insects in North America. Aside from a
small amount of nectar-feeding by adults, Pseudacteon flies
are completely dependent on ants. Indeed, most species of flies
under consideration for release as biocontrol agents of the RIFA
are restricted to a single species or species group of fire ants.
For example, native phorid species attack our native fire ants,
S. geminata and S. xyloni. The fact that in over seven
decades, no switch by native phorids to the invading S. invicta
has occurred is strong evidence of how extremely host-specific these
Why should we be concerned about studying our native species of
ant-attacking phorid flies?
of flies, genus Pseudacteon, that live, reproduce, and thrive
on host fire ants in North America can reveal much about details
of phorid natural history. Understanding the biology of these temperate-zone
phorids could provide important guidance for developing optimum
methods for introducing phorids from South America which would attack
the pest fire ant species.
Who funds fire ant/phorid fly research at The University of Texas
1986, work on the fire ant invasion was carried out by students
as part of undergraduate honors projects and graduate thesis and
dissertation research. Between 1986-1994, we were funded by the
Texas Department of Agriculture, American Farm Bureau Research Foundation,
and USDA Competitive Grants program. From 1994-1997, we received
funds from the following foundations and agencies: Dougherty Foundation,
Ewing Halsell Foundation, Fondren Foundation, Houston Livestock
Show & Rodeo, Robert J. Kleberg, Jr. and Helen C. Kleberg Foundation,
National Science Foundation, and Texas Parks and Wildlife Department.
From 1997-2004, our major funding has been through the Texas
Imported Fire Ant Research and Management Project that supports
research efforts of Texas A&M University, Texas Tech University,
The University of Texas, the Texas Department of Agriculture, and
others and is administered by the Texas Extension Station (TES).
During this time, foundatoins supporting our effort included The
Robert J. Kleberg, Jr. and Helen C. Kleberg Foundation, The Lee
and Ramona Bass Foundation, and Worthington Charitable Fund. This
is the nation's most innovative cooperative effort to eliminate
the pest status of an exotic organism. For further information contact
Bastiaan Drees (firstname.lastname@example.org).
How do you communicate your project goals and results to the general
to newspaper, magazine, radio, and TV reporters are given when requested
by the media or when we have a breakthrough to announce. Scientific
presentations are made at local and national
conferences and articles submitted to professional
I am very allergic to fire ant stings. Is it possible to have successful
immunotherapy as a protective measure?
there have been no controlled trials of IFA immunotherapy, a reasonable
support for the current clinical approach is Dr. Ted M. Freeman's
"IFA Immunotherapy: Effectiveness of Whole Body Extracts", Journal
of Allergy and Clinical Immunology, Vol 90 pgs 2150 ff, 1992. Conducted
at the Wilford Hall Medical Center (Air Force hospital) allergy
clinic in San Antonio, the study reports that 11 patients with IFA
sensitivity refused immunotherapy. Six of the 11 received subsequent
field stings and all six suffered anaphylaxis. However in the more
than 60 people who had received immunotherapy, about 47 suffered
field stings and only one reported a mild anaphylaxis. The p value
for immunotherapy providing protection from subsequent sting reaction
was <0.0001. Though not perfect, the results suggest that immunization
can protect against anaphylaxis. During sting challenges of some
30 patients on maintenance doses of immunotherapy, only one person
reacted to an IFA sting. He believes that pure venom would make
a much better research tool than WBE (whole body extract). Unfortunately
there is no commercial product available and extraction of venom
to do medical research is tedious.
a. What do fire ant stings look like?
high resolution photograph
(194K) illustrates the pustules that may result the day after being
stung. Each pustule represents a separate sting.
What causes the pustules?
article (28. below) describes two components of imported fire ant
(IFA) venom: proteins and alkaloids. The immune response, especially
IgE (an antibody, "immunoglobulin E"), is generally to
the protein component of foreign substances - 4 in Solenopsis
invicta (the red IFA) and 3 in Solenopsis richteri (the
black IFA). There is evidence that people who are sensitive to IFA
have IgE to the venom proteins. Freeman is unaware that anyone has
demonstrated IgE to the alkaloids. He feels the alkaloids are responsible
for the local cell necrosis that produces the fairly typical and
nearly pathognomonic (i.e., distinctively characteristic of a particular
disease) "psuedo-pustule" of the IFA sting. This is psuedo because
a true pustule is composed of an active neutrophilic infiltration
fighting an infection. In the case of the IFA reactions, the infiltrate
is just dead cells and there is no infection.
How can I treat fire ant stings?
after being stung, wash off the area with alcohol, try not to scratch
it so it doesn't get infected . Sometimes a white pustule will form
the second day, but it will eventually be resorbed. Commercial preparations
such as StingEze, etc will numb the area for a while. A thick paste
of baking soda and water can also help right after the sting. Careful
application of ice will help decrease pain, but can burn the skin
if left on too long. Meat tenderizer can also burn the skin. If
the pustule becomes infected, apply an antibiotic and see your doctor.
OTC Benedryl may help with local reactions: burning and itching.
Follow label instructions carefully.
other reactions occur soon after the stings, i.e., difficulty breathing,
itchy rash, loss of consciousness, etc., get the person to an emergency
room immediately. About 1% of the population have the potential
for serious and dangerous reaction to fire ants. A physician can
prescribe an EpiPen (single dose epinephrine auto injector device)
to carry with you in case of subsequent ant stings and anaphylactic
What has your research with phorid flies produced so far?
the last few years, we have studied about a dozen species of Pseudacteon
phorid flies in Brazil and Argentina which attack fire ants in their
homeland. With colleagues in those countries and in coordination
with colleagues at USDA in Gainesville, FL, we have learned about
the life history, behavior, and host specificity of most of these
phorid species and have identified several as high priority for
application in biological control.
species of Pseudacteon phorids have been introduced successfully
to Texas. One, P. tricuspis, has now spread up to 15 miles
from release sites around Austin, TX and now occupies approximately
100,00 acres. The second species has established and is beginning
in South Texas have not been as successful and we are now working
in Texas-like areas of Argentina in order to find phorid species
already adapted to climatic conditions to be encountered south of
San Antonio. We have identified several Argentinean species "of
interest" and are working to develop laboratory cultures.
Do fire ants destroy plants?
ants probably don't kill plants but they can diminish their health
and vigor by tending aphids and mealy bugs on stems and roots.
How much money do fire ants cost us?
to a study at Texas A&M University, fire ants cost the economy
of Texas over $1 billion per year.
How can we introduce phorid flies in our county?
have recently began a pilot program to assist local extension agents
and private interest groups to participate in acquiring their own
phorid "infections." Fire ants are collected in the area
to be treated with phorids according to our instructions. Ants are
separated from soil at Brackenridge Field Laboratory. We show participants
where to place out trays of ants in phorid fly "hot spots."
The flies will arrive and attack the fire ant workers. These phorid
fly-infected ants are then transported back to their home colony
and reintroduced. Establishment of phorid populations will require
multiple replicates of this process over 6 weeks.
I was stung by an ant that is fairly large (1.5cm) red with white
rings around the tail-end. They can "hiss" and seem to travel alone.
What kind of ant is this?
We have large ants that are furry with an orange furry back with
a black belly.
Are either of these fire ants?
are not ants, but rather a wingless solitary (non-social) female
wasp in the family Multillidae. Females are wingless and typically
colorful; males have wings. The common name for the group is "velvet
ants." Here in Central Texas we have about 40 species of velvet
ants, some small and some big. The "hiss" is called "stridulation"
and is caused by washboard-textured body segments rubbing rapidly
against one another. That and the coloration are warning signals
to potential predators. Some species could be described as furry.
a kid I made the mistake of handling one in south Texas called "cow
killer." I've had great respect for these critters ever
since. They mind their own business if not bothered. Most
are very beautiful and neat to have around. Their color is
a warning not to get too close. For information and a photo, see
Why do we have so many imported fire ants in Texas?
Texas possesses extensive open grassland and pasture habitats favored
by Solenopsis invicta. But also, in Texas we have the multi-queen
variety of fire ant which may have up to 100 reproductive queens
per mound. Multiple-queen or polygyne S. invicta do
not display the territorial conflict that promotes spacing between
colonies in the single queen or monogyne form found in South America
and in the SE United States. In Texas therefore, mound densities
can be much higher than in regions dominated by the monogyne form.
When the ground is dry, fire ant mounds disappear. Are the mounds
ant brood (babies) are sensitive to temperature and humidity. Worker
ants move the brood up high when it is wet. That's why you see tall
mounds after rains. When conditions are dry, they move the brood
deeper to more humid chambers and you may see no mounds at all.
Mounds can extend as much four feet below the surface.
Can you describe the life cycle of fire ants?
is a thumbnail outline:
egg laid by queen 2. larva hatches and grows through 4 larval developmental
stages or instars between which molts of larval skin occur 3. at
4th molt a pupa is produced 4. pupa hatched into adult ant.
are two basic types of eggs.
unfertilized eggs become males with wings whose only function
is to mate with queens
fertilized eggs become females which are either
winged virgin queens or
b. various castes of sterile workers.
the colony feeds and cares for female larvae determines their caste;
i.e., whether they behave as workers (all are sterile females) or
queens. Male ants develop from unfertilized eggs and therefore possess
only one set of chromosomes; i.e. they are haploid. Thus male ants
have no father (but they have a grandfather). Females develop from
fertilized eggs and are typical diploids. This type of life cycle
occurs in other so-called eusocial insects including wasps, bees,
and ants and is called "haplo-diploidy." Eusocial insects possess
sterile castes that help queens by raising other siblings. Why some
individuals give up the option to reproduce has been an interesting
evolutionary dilemma since the time of Darwin but the work of people
like the late W.D. Hamilton has largely solved the problem.
How do fire ants spread?
ants reproduce opportunistically when conditions are wet and warm.
are found in all types of soil, but they do better in open pastures
and sunny, grassy places than in thick shaded woods. Grassy medians
of freeway and mowed pipeline and powerline rights of ways provide
prime "freeways" for the ants too.
colonies (those with multiple queens/mound) can reproduce by budding
off new colonies and spread by walking a few meters per year. Colony
establishment by winged queens can occur miles beyond source populations.
This mode of spread may be promoted by prevailing winds and is the
only way that monogyne or single queen colonies reproduce. Judging
from the spread across Texas, natural dispersal was on the order
of 10-20 miles/year. Of course transport in nursery products spread
the ants beyond the boundary of natural dispersal. Though fire ants
may arrive in the NE U.S. and Canada via nursery products, nests
in RVs, cars, vans, etc., they are not likely to become a problem
because of the cold conditions in fall spring and winter.
What can I use to kill fire ants indoors? I don't want to expose
my family and pets to dangerous chemicals.
you can avoid pets and kids you could consider making these same
baits available in the house as well. Don't bradcast there but put
baits in corners under, appliances and in closets. Indoors, I've
also used boric acid (15% by volume) in peanut butter placed in
bottle lids where ants have trails. Boric acid works in similar
fashion, killing slowly after distribution among colony members
(it also kills cockroaches when mixed with cornmeal and sugar).
It will take about 2 weeks to completely control them, but is very
effective. Treating the inside alone will never work since ants
killed there are quickly replaced by a large population outdoors.
Why not kill all the ants in my yard just to be sure I kill the
ants compete for food with fire ants and help keep them under control.
If you kill all ants in your yard, you create an "ant vacuum"
and after the next rain, it will be fire ant queens that land in
your "safe" yard to begin new mounds unopposed by any
other ants. Fire ants are better at colonizing and dominating newly
disturbed habitat than the average ant species.
native ants are not harming you but simply sharing their habitatwith
you, I would suggest leaving them alone. Often when one removes
a native element of the ecosystem, something much worse fills the
void. In Texas, our worst fire ant problems are in areas where
people blasted the native system with pesticides and made invasion
by introduced pests more likely.
Why are phorid flies better than pesticides in controlling fire
flies may not be better than pesticides in many local, short-term
circumstances, so there will always be role for some careful use
of pesticides. However, over an entire region and over decades,
biological control agents like phorid flies are likely to be a more
economic and safe way to reduce the pest status of imported fire
Do fire ants sting or bite? Why didn't I feel any ants on me
until I was stung multiple times?
ants bite and then sting! One feels a prickly sensation as the ants
bite the skin's surface with their mandibles to get a grip. The
bite does not inject venom, rather this gives them a solid anchor
at the head end, while they jab the stinger (a hypodermic-like device
modified from the ovipositor, the egg laying structure) into the
victim, injecting a toxic alkaloid venom from a special gland and
at the same time releasing an alarm pheromone (chemical signal)
that excites additional attackers. Fire ants do not inject formic
acid, as in the case in many ants. (Not all ants sting, but fire
ants do and it is the venom injected by the sting that people react
to. Some other ants that don't sting do bite and then squirt venom
onto the area of the bite.)
strychnine, nicotine, morphine, and caffeine are also alkaloids.
Someone suggested that pouring gasoline on fire mounds was a certain
way to kill them. What do you think?
is as dangerous to the applicator as it is to a fire ant colony.
That's a common, but inefficient and ill-advised, approach. Gasoline
would be a very expensive, environmentally harmful method if applied
on the scale of acres rather than one or two mounds.
I heard that if fire ants get into the walls of a house, they can
do an much damage as termites. Is there some ant that does this
and if so should we be concerned about them in Texas?
ants (genus Campanotus) are termite predators and move into
old termite galleries or into wood softened by fungus. As a result
they are accused, perhaps unjustly, of creating serious structural
damage. I view them as a symptom rather than a cause. Fire ants
will eat both Campanotus larvae and termites, but not wood.
Fire ants also transport dirt into walls, circuit boxes, etc. but
do not damage wood structures directly.
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