Yellow Crazy Ant

Anoplolepis gracilipes

Last updated: November 17, 2022
Verified by: AZ Animals Staff
© frank60/Shutterstock.com

Instead of biting or stinging, these pests spray an acid to weaken or kill their target.

Yellow Crazy Ant Scientific Classification

Kingdom
Animalia
Phylum
Arthropoda
Class
Insecta
Order
Hymenoptera
Family
Formicidae
Genus
Anoplolepis
Scientific Name
Anoplolepis gracilipes

Read our Complete Guide to Classification of Animals.

Yellow Crazy Ant Conservation Status


Yellow Crazy Ant Facts

Prey
mollusks, earthworms, land crabs, small reptiles, small birds, and small mammals
Name Of Young
larva
Group Behavior
  • Colony
Fun Fact
Instead of biting or stinging, these pests spray an acid to weaken or kill their target.
Estimated Population Size
unknown
Most Distinctive Feature
long legs
Distinctive Feature
long "neck" and yellow color
Other Name(s)
long-legged ants, Maldive ants.
Temperament
erratic
Habitat
tropical lowlands
Predators
no natural predators
Diet
Omnivore
Lifestyle
  • Nocturnal/Crepuscular
Favorite Food
honeydew
Common Name
yellow crazy ant
Origin
africa or asia, undefined
Slogan
One of the top 100 worst invasive species!

Yellow Crazy Ant Physical Characteristics

Color
  • Brown
  • Yellow
  • Red
  • Orange
  • Golden
  • Light-Brown
Skin Type
Exoskeleton
Length
four to five millimeters
Venomous
No
Aggression
Low

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The yellow crazy ant is so called because of its color, as well as the frenetic movements it makes when disturbed. Unlike other ant species, these pests don’t bite or sting – they spray acid! Yellow crazy ants may be tiny, but they have decimated ecosystems and are behind millions of dollars’ worth of damage.

Facts

  • Unlike most other ant species, yellow crazy ants have multiple queens and live in supercolonies.
  • Yellow crazy ant supercolonies are sometimes the largest in the world. The largest span over a hundred hectares and house up to 20 million ants per hectare!
  • When bothered, this ant makes erratic movements, which is why it is described as being crazy.
  • Don’t underestimate these tiny pests. Yellow crazy ants destroy ecosystems and cost countries millions of dollars in damages.
  • Unlike other ant species, yellow crazy ants don’t bite or sting. They spray formic acid instead which blinds, overwhelms, and can even kill their target.

Scientific Name

The yellow crazy ant belongs to the genus Anoplolepis. It is classified as Anoplolepis gracilipes, although some scholarly papers use its synonym, Anoplolepis longipes, instead. The genus name Anoplolepis is derived from two Latin words meaning “without scales.” The species name, gracilipes, is also Latin-derived, and it means “thin-legged.”

Yellow crazy ants are generally yellow with tone variations ranging from red to gold to brown. When bothered, this ant makes erratic movements which is why it is described as being crazy.

Members of the genus Anoplolepis are known as pugnacious ants because of their aggressive nature. They belong to the order Hymenoptera and the family Formicidae. Hymenoptera is a large order of insects that contains over 150,000 extant species of insects and 2,000 extinct species. Other animals that belong to the order Hymenoptera are wasps and bees.

Yellow crazy ants are also called long-legged ants and Maldive ants.

Appearance

Yellow Crazy Ant Walks on Moss
Compared to other ants, yellow crazy ants are large. Worker ants have an abdomen that is darker in color.

©frank60/Shutterstock.com

Yellow crazy ants are comparably large and have long, slim bodies. The worker ants possess dark-colored abdomens. Their defense system, the acidopore, is on the abdomen along with erect hairs. They do not have stingers. Yellow crazy ants are also known as long-legged ants. This is a befitting nickname, because of their relatively long legs and antennae. Their antennae contain 11 segments and are 1.5 times longer than their heads.

Just like their name suggests, yellow crazy ants are yellow and may have either a golden, reddish, brownish, or orangish tone to them. Their abdomen is usually brownish and may have stripes. The ants have a length of about four to five millimeters. Yellow crazy ants have oval-shaped heads and mandibles with eight teeth each. They also have a petiole which is a waist segment that is round and elevated.

Habitat and Population

The yellow crazy ant is an invasive species. They have managed to permeate numerous regions of the world where they wreak havoc on ecosystems.

The exact origin of the yellow crazy ant is unknown. Many believe them to be native to either Africa or Asia. The confusion stems from the ant’s history being conveyed from one location to the next by unintentional human interference. Yellow crazy ants are spread unknowingly within cargo on ships, freight, and other means of human movement.

Today, yellow crazy ants have naturalized in several countries and tropical islands worldwide. These include China, India, Indonesia, Malaysia, Myanmar, Philippines, Singapore, Sri Lanka, Thailand, Vietnam, South Africa, Tanzania, Brazil, Panama, Mexico, and Australia. They are especially notable in places like Christmas Island, where the population has increased exponentially in recent decades. These ants inhabit several habitats, such as lowland tropical forests, and coconut, citrus, and coffee plantations. They move from these habitats to others with the help of trucks and other forms of human transport that carry these agricultural goods to different locations.

Yellow crazy ants have their own natural means of dispersal known as “budding.” This process occurs when a queen and her workers leave the colony to start a new one. However, this does not usually occur through flight, therefore they don’t get very far. They require human interference to spread across far distances. Yellow crazy ants move up to 1,300 feet and 0.6 miles annually in the Seychelles and on Christmas Island, respectively.

These invasive ants are also present in human-populated regions, which means that they are capable of inhabiting buildings and other places frequented by people, although they are not prone to. On Christmas Island, yellow crazy ants have decimated the land crab population and negatively impacted the ecosystem. The yellow crazy ant is in the IUCN Global Invasive Species Database as one of the top 100 most invasive species.

Evolution and History

Anoplolepis gracilipes is the only invasive species of the genus Anoplolepis. The native history of this species of ant is still widely debated. All of Anoplolepis’s nine species and five subspecies are native to Africa, except Anoplolepis gracilipes. This is a strong argument in favor of Africa being its native region. However, many biologists have suggested that Anoplolepis gracilipes might be native to some tropical Asian regions.

Yellow crazy ants belong to the ant family Formicidae, the members of which evolved from vespoid wasps during the Cretaceous Period tens of millions of years ago. The oldest ant fossils found date back 100 million years ago. Those belong to some now-extinct groups, such as the Haidomyrmecinae, Sphecomyrminae, and Zigrasimeciinae. Modern subfamilies of ants started showing up about 80 to 70 million years ago.

Yellow crazy ants belong to the subfamily Forminicae, because they do not possess stingers and their pincers are more moderate than members of other subfamilies. Instead, they possess acidopores which are tiny holes at the tip of their abdomens that spray formic acid onto their prey or assailant. This acid serves to weaken, blind, or even kill their target.

Diet

The yellow crazy ant is opportunistic and will eat whatever it can find. They are capable of destroying entire ecosystems with their predatory behavior. These ants prey on invertebrates like mollusks, earthworms, land crabs, and smaller vertebrates such as small reptiles, small birds, and small mammals, if the ant population is large enough. Yellow crazy ants are also scavengers. They spray formic acid on their target prey which causes blindness and eventually death by malnourishment. The exact diet of yellow crazy ants depends on their geographical location.

Yellow crazy ants depend largely on honeydew produced by scale insects that feed on plant sap to produce the sugary liquid. These pests are shepherded by the ants who offer them protection from their natural predators in return for the honeydew.

What Eats Yellow Crazy Ants?

In many countries, the yellow crazy ant has no natural predators. However, in Sulawesi, an Indonesian island, a native species of toad (Ingerophrynus celebensis) feasts on them regularly.

Behavior

Yellow crazy ants are typically nocturnal or crepuscular in nature because they mostly hunt at night and early in the morning.

These ants build their nests in numerous places, including the ground under trees or in the canopy, and rotten logs. They are known to form some of the largest colonies of any species of ant in the world, with colonies spreading across 10 to 150 hectares housing up to 20 million worker ants per hectare of land.

Just like many other ant species, yellow crazy ants have mutualistic relationships with scale insects, aphids, and other pests that produce honeydew by sucking plant sap. They take care of and protect these insects from predators, shepherding them around, and in return, they eat the honeydew they produce. The pests destroy the plants that they feed off of, as well as encourage the growth of sooty mold when the sugary honeydew drips on the leaves and stems. The relationship between yellow crazy ants and scale insects is so strong that in one study in which researchers removed the crazy ants from an area, the population of the scale insects dropped in population by 67% in 11 weeks. They eventually disappeared completely after a year.

Reproduction and Lifespan

Yellow crazy ants differ from most other ant species in that they don’t have just one any queen – they have many. Yellow crazy ants build supercolonies with up to 300 queens in it. Some of these supercolonies extend over 150 hectares and make up the world’s largest colonies of any species of ants.

Creation of offspring is highly dependent on the rainy season. Yellow crazy ant eggs can be produced at any time during the year but usually one to two months before the rainy season. Workers are produced throughout the year with some variability.

Yellow crazy ant eggs hatch into larvae after 18 to 20 days and how quickly the larvae develop depends on whether it is a worker or a queen. Worker larvae develop in 16 to 20 days while queen pupae develop in 30 to 34 days.

Yellow crazy ants create new colonies through a process called “budding,” wherein a queen or queens leave the nest with some workers to create a new colony elsewhere. Although this process is slow because they rarely ever disperse by flight, it is still quite effective and they cover substantial distances annually. Yellow crazy ants rely on human movement to broaden their reach.

Yellow crazy ant workers have a lifespan of about 76 to 84 days while queen yellow crazy ants can live for many years.

Prevention: How to Get Rid of Yellow Crazy Ants

Yellow crazy ants are an invasive species and they can inhabit human-populated areas such as houses and other buildings. If you believe you have an infestation, then the first thing to do is check around to find them. Yellow crazy ants can inhabit soil, timber, agricultural produce, construction items, and packaging. Then, identify the ants to make sure they are yellow crazy ants.

Yellow crazy ants can be controlled by baiting or spraying. The baiting process involves regulating the growth of the ants by using a liquid or gel that is to be ingested. The bait would contain a fake juvenile hormone that mimics the real hormone that controls the ant’s growth, fertility, pupation, and egg viability. This will lead to failures in the ant’s reproductive cycle and reduce their worker population, resulting in starvation.

Spraying involves the use of pesticides, which should be employed carefully. Make sure you read and understand the instructions on the label before you use it. It is also advisable to contact a professional exterminator to administer the pesticide correctly.

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About the Author

Hi! I am a writer, actor, and filmmaker. Reading is my favorite hobby. Watching old movies and taking short naps are a close second and third. I have been writing since childhood, with a vast collection of handwritten books sealed away in a duffel bag somewhere in my room. I love fiction, especially fantasy and adventure. I recently won the James Currey Prize 2022, so now, naturally, I feel like I own words. When I was 11, I wanted to be a marine biologist because I love animals, particularly dogs, cats, and owls. I also enjoy potatoes and chocolate in all their glorious forms.

Yellow Crazy Ant FAQs (Frequently Asked Questions) 

Do yellow crazy ants bite?

Yellow crazy ants do not bite or sting as their mandibles are greatly reduced and they do not possess stingers. Instead, they spray formic acid which comes out of their acidopore, an opening on their abdomen.

Can yellow crazy ants kill humans?

The formic acid sprayed by yellow crazy ants are not known to have ever killed anyone. However, enough sprays from enough ants can cause irritation in the skin and eye.

How do I get rid of yellow crazy ants?

A combination of spraying and baiting would help to get rid of these pesky insects. Baiting will help slow their reproductive cycle while spraying will kill them directly.

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.

Sources
  1. Cabi Digital Library, Available here: https://www.cabi.org/isc/datasheet/5575
  2. Wet Tropics Management Authority, Available here: https://www.wettropics.gov.au/yellow-crazy-ants
  3. Queensland Department of Agriculture and Fisheries, Available here: https://www.daf.qld.gov.au/__data/assets/pdf_file/0003/63372/IPA-Yellow-Crazy-Ant-Risk-Assessment.pdf
  4. Wikipedia, Available here: https://en.wikipedia.org/wiki/Yellow_crazy_ant
  5. Wikipedia, Available here: https://en.wikipedia.org/wiki/Hymenoptera
  6. Jung, Jae-Min, et al., Available here: https://www.sciencedirect.com/science/article/pii/S2287884X1730095X#:~:text=The%20yellow%20crazy%20ant%20(Anoplolepis%20gracilipes)%20is%20the%20only%20insect,natural%20predators%20(Wetterer%202005).

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