I. b. Imported Fire Ant Identification and Biology

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I. b. Imported Fire Ant Identification and
Biology

• Teaching Module for Master Gardener Training

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Identification

• Location found in open, sunny areas
• Mounds large, no activity on surface
• Ants very aggressive when disturbed
• Stings Painful, leave white pustule, sting more
  than once

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Medical Importance
Pustules
Bite and Sting Multiple Times

Stinger and Poison Gland
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Types of Adult Fire Ants
Winged female
Winged male
Workers
UC Statewide IPM Program
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Polymorphism in Worker Ants
major
queen
minor
media
Adult fire ant workers have different morphs
(polymorphic), i.e. major, media and minor that
vary greatly in body size. Majors are often used
in identification because of their large size.
Not all ant species exhibit polymorphism.
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Reproduction

• Mating flights on sunny days 1-2 days after a
  rain when temperatures are above 75ºF
• Flights usually occur in spring and fall but can
  occur at any time of year

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Reproduction

• Mating takes place 300 to 800 feet above the
  ground.
• After mating, female seeks moist or reflective
  surfaces on which to land male dies.
• Female vulnerable to predators during and just
  after mating flight, especially other fire ants.

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Colony Formation

• New colonies are founded by newly mated females
  (queens).
• Once a queen lands, she removes her wings,
  burrows into the soil and begins to lay eggs.

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Colony Formation

• First batch of eggs grows up to be worker ants.
  
• Worker ants are all sterile females capable of
  stinging.
• Workers begin foraging and constructing mound.

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Colony Formation
A queen can live 5-7 years and lay up to her own
weight in eggs per day (800-3000 eggs).
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Development
Worker immature and mature stages

• Large workers live about 90-150 days as adults
• Small workers live about 60-90 days as adults
• Regardless of size, they change jobs as they age
• nurse
• guard/excavator
• forager

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Mound Development

• Mounds often are not clearly visible within
  first few months.
• A small mound with several thousand ants may be
  visible within six months.

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Mound Development

• Fire ant mounds can be recognized by their dome
  or cone-shape.
• Mounds can be quite large (sometimes 60 cm tall
  and 60 cm wide).
• Mounds usually found in open areas.
• Unlike the nests of most other ants, fire ant
  mounds have no openings and little visible
  activity on the mound surface, unless disturbed.

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Lateral foraging tunnel Exit / Entrance
Interconnected chambers
Lateral foraging tunnel
Deep tunnels to water source
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If the mound is disturbed, the workers rush to
save the queen and the immature ants.
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Workers move the immature fire ants and the queen
around the nest, for near constant temperature
and humidity, often more than once per day.
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The fire ant has 4 life stages
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Larval Stages
Larvae molt four times over a 12-15 day period.
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Fourth instars are the only stage that can feed
on solid food (black arrow points to food
particle).
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Food Sources
Fire ants eat a variety of foods
Reagan, LSU AgCenter
and are excellent foragers.
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Trophallaxis

• Foraging ants bring the food back to the nest.
• The ants pass the food to one another by
  regurgitating it from their crops as liquid until
  food is distributed to all members of the colony,
  including the queen (trophallaxis).
• Adults cannot digest solid food.

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Single Queen Colony

• 15-80 mounds per acre, 7 million ants per acre
• One queen per colony
• Worker ants are territorial
• The majority of fire ant colonies are of the
  single queen type

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Multiple Queen Colony

• 200-800 mounds per acre, 14 million ants per
  acre
• More than one queen in each colony
• Colonies reproduce by budding
• Worker ants are not territorial
• Typical form in Texas

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Reproduction Type

• Single queen (monogyne)
• territorial and aggressive
• limited life to colony
• Multiple queens (polygyne)
• non-territorial and not aggressive toward each
  other
• will adopt new queens
• long-lived colonies