Ants – Armies of One

Ants are one of the most successful species in Earth’s history, having been here for over a hundred million years. They colonized every continent except Antarctica (long before us) and are one of the best known species to act as superorganisms – which means to take action in mass numbers toward the common benefit of the colony. Their specialized divisions in class and the way they work together resemble humans but some species of killer ants have biological weaponry powerful enough to kill many of us every year. Out of the 12,000 species of ants currently classified at Harvard University, these five are the deadliest not just to humans but to larger animals and ecosystems where they are invasive.

Fire Ants

Fire Ant

Fire ants (0.24 inches long) have been a widespread problem in the United States after they were accidentally introduced in the 1930s. Known for their large ant mound colonies and aggressive nature, they attack in swarms following pheromones released by the first ant’s sting. So if you are stung once, you are bound to get attacked by the entire colony if you can’t get away quick enough. Small animals such as birds and even larger mammals like newborn calves often become victims because they cannot escape in time before they are devoured en masse.

Fire ant stings are sharp, immediate, and induce a burning irritation – hence the name “fire” ant. The pain of the sting is listed on the Schmidt Pain Index with a rating of 1.2; painful but not the worst. The venom causes white pustules to show up on the skin twenty four hours after being injected. To date the species is an ongoing pest problem because it is highly resistant to methods of control and it can adapt to many changing environmental conditions. Some humans are sensitive to the venom and may die from anaphylactic shock in minutes if left untreated.

Argentine Ants

Argentine Ants

The Argentine ant (1/10 inch long) is highly social ant species, known for extensive organization of its colonies. In fact, the ants are so genetically similar that individual ants can walk into a range of nearby colonies without being killed for intrusion. Merged supercolonies are destructive, especially if near human settlements. The problem with Argentine ants is that they are among the world’s top 100 animal invaders, known for killing off competing ant species in non-native geographical areas, such as in Australia. In the article linked above, the scientists state that an Argentine ant supercolony thousands of miles wide can form across southern Australia if the native ants of that region have the same genetic makeup and behavior.

As pests they have a tendency to enter human built structures in search of food and even form colonies. Killing off a single queen to solve the problem won’t work because Argentine ants typically have eight queens for every 1,000 workers. Spraying pesticides only increases the rate of eggs the queens lay so that’s not recommended. To humans, these ants are of medical importance, because they have the potential to carry disease causing pathogens into hospitals.

Siafu Ants (also known as the Driver ant or the Army ant)

The Siafu ants (Army ants) of Western Africa and the Congo have functional stings but the reason why they’re notorious is because of their razor-sharp cutting mandibles, which you just can’t miss if you saw a picture of one. The colonies are made up of different classes making up enormous colonies and the queen Siafu ant holds the record for being the largest ant in the world.

Army Ant Jaws

The ants march through the forests in groups of millions, eating anything that moves and severely impacting the local environment (even elephants run from them). The term “killer ant” usually applies to this species simply because of the magnitude of the colony sizes (over 20 million individuals). When in large transit, the ants travel in long columns on the forest floor, with the stronger class of ants on opposite sides flanking in ready position – jaws ready. They are so strong in fact, that you can tear the ant in two after it bit into your skin and its jaw will still be locked in position. In East Africa, emergency situations call for using the actual jaws of the Siafu ants as ‘stitches’, sealing off open wounds.

The reason why this species is so deadly is the fact that the ants are virtually unstoppable as they move together in full force. Anything that gets in the way is eaten to the bone – no exceptions. The columns are easy to avoid but sometimes they come across human homes, in which case the potential to kill becomes greater.

Bulldog Ants (also called Jack Jumpers)

Bulldog ants reign from Australia and are among the largest ant species in the world, growing over 40 mm long. Their appearance alone is enough to tell you they are deadly and capable of killing. Bulldog ant is also one of the oldest ant species, with its closest relative only found in fossils.

Even scarier is the numerous predatory skills they have compared to other ant species, such as excellent vision (they can spot and follow you from a meter away), highly painful stings that can cause anaphylactic shock in allergic people, and they are very aggressive to intruders, including humans. This combination makes them responsible for the deaths of people every year in Australia.

Bullet Ants

Bullet ants of South America are known to have the most painful sting of insects on the entire planet, rated at the highest of the Schmidt Pain Index at 4.0+. The name of the ant is derived from the intense 24-hour pain the venom from the stings cause. Bullet ants are also giants, ranging from 18 to 25 mm long (1 inch). The venom is highly neurotoxic, causing excruciating pain when injected into mammal smooth muscle. When attacked, these killer ants release a musky order, swarm together to defend against the intruders, and literally grab and sting them to death.

Some tribes in South America knock out the bullet ants with natural chloroform and weave them into the inside of gloves, stingers outward. The boys must wear the gloves and endure every single sting from the awakening bullet ants for ten full minutes without screaming. This is part of the initiation into manhood and a boy cannot truly ‘become a man’ until he completes this ritual 20 times. After each ordeal, the arms become paralyzed and quiver for days.


Tatiana Giraud, Jes S. Pedersen, and Laurent Keller, “Evolution of supercolonies: The Argentine ants of southern Europe,” PNAS April 30, 2002, Vol. 99, no. 9, 6075-6079.

Harris, R J (2002) Potential impact of the Argentine ant (Linepithema humile) in New Zealand and options for its control. Science for Conservation 196 PDF

Fowler, H.G.; Bueno, O.C.; Sadatsune, T.; Montelli, A.C. 1993: Ants as potential vectors of pathogens in hospitals in the state of Sao Paulo, Brazil. Insect Science and its Application 14: 367-370.

Forbes McGain and Kenneth D. Winkel (2002) Ant sting mortality in Australia Toxicon. 40(8):1095-1100