Red Imported Fire Ants In Miami Florida

Fire Ants HYMENOPTERA: FORMICIDAE Red Imported Fire Ants RIFA Solenopsis invicta Buren RIFA is native to central South America. RIFA was first introduced In the US, from Brazil into either Mobile, Alabama, or Pensacola, Florida, between 1933 and 1945. Which have made it all the way down to Miami as far as the Keys.

fire ants
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Identification and Anatomy of Red Imported Fire Ants

Workers are polymorphic they are many sizes between Minor Worker, Medium Worker, Major Worker 1/8 to 1/4

RIFA has a two segments The pedicel, or “waist” 

The mandible has four distinct teeth.

Has a 10-segmented antennae ending in a two-segmented club

A stinger is present at the tip of the gaster.

Biology and Life Cycle

Has a complete metamorphosis the brood consists of egg, larvae pupae.

The larvae develop through 4 progressively larger stages called instars.

The last larval instar becomes a pupa.

Adult RIFA Casts Minor Worker, Medium Worker, Major Worker and Queen.

The lifespan of RIFA workers depends on their size.

  • Minor workers may live 30 to 60 days,
  • Median workers 60 to 90 days,
  • Major workers 90 to 180 days, and
  • Queens may live 2 to 6 years.

A complete lifecycle from egg to adult takes between 22 and 38 days

Mating flights (Altates) of Red Imported Fire Ants

These flights are when adult males and females generate wings and leave the colony to mate in what are known as nuptial flights.

This is the primary means of colony propagation

Budding is a secondary means of propagation where a queen and members leave the colony to create a new one, this happens when a portion of a colony becomes an autonomous unit.

Reproductive alates are produced after the colony reaches 1 year of age.

Mating flights occur between the spring and fall with 6 to 8 mating flights consisting of up to 4,500 alates each.

Mating flights typically occur midday on a warm sunny day following rain when temperature are less than 74°F

Mating happens in flight and the males die shortly after mating with females.

As many as 97,000 queens may be produced per acre, per year In the southern United States once the land is infested.

Alates winged ants are regularly attracted to swimming pools typically winged ants are trapped on the water’s surface.

Newly-mated queens will cluster together under shelter.

This clustering aid in establishing a colony.

Once the colony grows only one queen will remain alive.

This is an exception in multiple queen colonies.

Recently mated femals will rake their legs forward to snap her wings off and find a spot to begin a new colony

The spot often under rocks, leaves or in a small crack or crevice, such as at the edge of a sidewalk, driveway, or street.

The queen burrows into the soil to excavate a small chamber, which she then seals off to keep predators out.

She will lay between 10 to 15 eggs within 24 hours of mating,

The newly laid eggs will hatch in 8 to 10 days.

By the time the first group of eggs hatches, the queen would have laid between 75 to 125 additional eggs.

The larval stage typically lasts 6 to 12 days

The pupal stage lasts from 9 to 16 days.

The newly-mated queen will stop laying eggs until the first batch of workers mature.

The entire process takes from 2 weeks to 1 month.

The queen will feed the first batch of young larvae

  • Oils regurgitated from her crop
  • Trophic eggs
  • Secretions from her salivary glands.
  • The wing muscles.

The first workers to emerge are small due to the limitations of nutrients that the will queen provide.

These workers, called “minims,”

These small workers burrow out of the chamber and begin foraging for food to feed the queen and new larvae.

The minims will also begin construction of the mound.

Within the first month larger workers are being produced and the mound grows in size.

By 6 months the colony has reached several thousand workers by this time the mound is visable in a field or lawn.  

Colonies this size generally contain mostly small workers (minor workers), many medium sized workers (median workers),  and few large workers (major workers).

These 3 types of workers are all sterile females where the main tasks are to maintain the colony.

The queen is the only producer of eggs, capable of producing as many as 1,500 eggs per day.

A mature colony may contain as many as 240,000 workers a typical colony consists of 80,000 workers

Feeding Habits Of RIFA

The diet of foraging workers consists of dead animals, including insects, earthworms, and vertebrates.

Workers will also collect honeydew from pests like aphids, scale, mealybug, thrips, whiteflies, sugars, proteins, and fats in homes.

They are sometimes attracted to piles of dirty laundry.

Larvae of RIFA are fed only a liquid diet until they reach the third instar.

Only when the larvae reach the 4th instar are they able to digest solid foods.

Workers will bring solid food back which is rich in protein and deposit it in a depression in front of the mouth of the larvae.

The larvae will secrete the digestive enzymes that break down the solid food and regurgitate it back to worker ants.

The queen is fed some of the digested protein to support egg production.

Egg production is at its maximum as long as food is plentiful.

Sting and Venom Of Red Imported Fire Ants

Workers have a “stinger” which is a modified egg-laying structure called an ovipositor.

Worker ants are sterile females unable to produce eggs.

A gland containing the poison venom is attached to the stinger.

Queen and winged reproductive an unmated queen ant also has a poison gland but do not use their ovipositor as a stinger.

Worker ants bite down on the skin using their mandibles and will lower the tip of the gaster to inject the stinger into the skin.

Red Imported fire ants both bite and sting, however only the sting is responsible for the pain and puss.

The sting of the RIFA possesses venom of an alkaloid nature, which exhibits potent necrotoxic activity meaning it which destroys tissue cells.

About 95% of venom of the imported fire ant Solenopsis invicta is composed of dialkyl piperidines that cause both the pain and white puss that appears the day after a sting.

The re venom contains a solution of proteins, peptides, and other small molecules that produce the allergic reaction in hypersensitive individuals. Currently 46 proteins have been isolated 4 of which are well categorized as potent allergens.

Study suggest that the creation of puss may involve the activation of platelets and neutrophils.

Red Imported Fire Ant, Solenopsis invicta Buren (Insecta: Hymenoptera: Formicidae: Myrmicinae)

Other Fire Ants In the US

Native Fire Ants  Solenopsis geminata (Fabricius)

The southern fire ant Solenopsis xyloni McCook,

DESERT FIRE ANTS Solenopsis aurea Wheeler,

the black imported fire ant, Solenopsis richteri Forel, northeastern Mississippi and northwestern Alabama.


Medical Problems and Treatment Considerations for the Red Imported Fire Ant

Proteins Revealed In Fire Ant Venom

Chemical blueprints to identifying fire ants: overview on venom alkaloids

Control of Red Imported Fire Ants is achieved primarily with baiting utilizing several granular bait formulations that include synthetic baits with insect growth regulators.

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United States. Animal And Plant Health Inspection Service. Plant Protection And Quarantine Programs [Public domain]

Strongbad82 at English Wikipedia [Public domain]

Walter R. Tschinkel, Alexander S. Mikheyev & Shonna R. Storz  (2003). "Allometry of workers of the fire ant, Solenopsis invicta". Journal of Insect Science 3 (2): 1–11. DOI:10.1673/031.003.0201. PMID 15841219. PMC: 524642. [CC BY 3.0 (]