Known for constructing giant fungus farms tended to by millions of workers, leacutter ants are some of the most industrious ants known to science and rival us in terms of their organisational capabilities.
Like other ants, they’re highly social and live in colonies where individuals are divided into seven castes, each performing different tasks at the bidding of a ruling queen. A colony takes roughly 18 months to reach maturity and can survive for 10-20 years.
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How many species leaf cutter ants are there?
At least 55 species of ants are known to cut, chew, and process leaves. These ants fall into three main genera - Atta, Acromyrmex, and Amoimyrmex - all of which are part of the tribe Attini, commonly known as the fungus-growing ants. Not all species in this diverse tribe are leafcutters, some collect decaying plant matter, insect droppings, or fragments of wood to fuel their fungus farms.
Where do leaf cutter ants live?
These ants are endemic to South and Central America, Mexico, and parts of the southern US. They’re found mainly in tropical rainforests, but have also been recorded in more open habitats such as savannas and farmland, where they’re often regarded as pests. To construct their elaborate, underground nests, leafcutters dig deep into the forest floor, reaching depths of up to 9m.
How do they harvest leaves?
Using serrated mandibles that act like vibrating saw blades, specialised workers known as foragers cut semicircular pieces of leaves from living plants. They lift these fragments (which can weigh as much as eight times their body weight) in their jaws and carry them back to their nests, using a special groove on their head and a series of dorsal spines to keep their load steady. The mandibles of foragers are lined with zinc, giving them razor-sharp cutting edges. They also have powerful bites 2600 times their body weight.
What do they use leaves for?
Contrary to popular belief, these ants don’t eat the leaves they harvest. Instead, they use them to sustain the fungus they farm and harvest to feed themselves and their larvae.
After transporting leaves home (the equivalent of you carrying more than 500kg using just your teeth), foragers pass the work onto smaller ants who chew the leaves into a pulp, mixing in droppings and enzymes to create a nutritious mush their cultivated fungus then consume.
Other workers tend to these fungal plots, removing foreign spores and bacteria. Having been domesticated, this fungus is genetically distinct from its wild relatives and couldn’t survive without the help of these ants.
Is there any structure to their nests?
The nests of leafcutter ants are made up of thousands of climate-controlled rooms, resembling a structure not too dissimilar to an urban office block. Not all of these rooms are used for growing fungus. Some contain nurseries that house growing larvae, others are dedicated rubbish areas and storage facilities for dormant workers and excess leaf material. There’s also a chamber for the queen, where she’ll lay hundreds of eggs per day. These rooms are connected by a series of tunnels and ventilation shafts that are crucial for regulating temperature, humidity, and airflow within the nest.
How big are their nests?
A single nest can reach over 30 metres in diameter and extend several metres deep. The largest nest on record covered an area 67m², which is roughly the size of a small apartment. This nest was created by a species known as Atta laevigata and it contained 1,920 chambers, 238 of which were occupied by fungus gardens.
How do workers communicate?
Like most ants, leafcutters have poor eyesight and instead rely on chemical signals to communicate. As foragers head out in search of leaves, they’ll lay trails of pheromones to guide others along already trodden paths.
They also produce specific alarm pheromones to alert soldiers whenever they’re threatened or come under attack from rival colonies. A lot of leafcutters are also known to communicate via stridulation, whereby individuals use a specialised file on their abdomen to make vibrational ‘chirps’ that can signal for assistance, coordinate work, or raise alarms.
Do these ants go to war?
While they belong to a different lineage than army ants, leafcutters are also known to wage war. These wars can be extraordinarily bloody, with thousands dying each day on a single battlefront. Most of the time, leafcutters don’t start these conflicts; instead, they defend themselves when other ants, primarily army ants, invade their nests to feed on their larvae.
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What else preys on them?
As well as being a source of food for other ants, such as Nomamyrmex army ants, leafcutters are eaten by armadillos, anteaters, spiders, and various species of birds. With their long, sticky tongues and powerful digging claws, armadillos pose the biggest threat to leafcutters, as they can dig up entire nests and devour everything inside, from queens and workers to larvae and eggs.
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