Leaf Cutter Ants: The First Farmers

Leaf Cutter Ants: The First Farmers

Rainforests are among the most biodiverse places on Earth. Millions of years of evolution in these regions have resulted in some of the most amazing organisms ever known to man. Being able to survive in a harsh environment dominated by high temperatures and high humidity is a requirement more than a choice. These conditions promote plant growth and attract many arthropods. Insects are among the most diverse animals in the rainforest.  Butterflies are perhaps the most eye-catching of all with vivid colors and metallic shine, some using these colors to warn off their toxic nature.  Beetles, grasshoppers and leaf insects all munch on the exuberant vegetation with little remorse for the plants they are eating.


But those who visit the rainforest will rarely do so without crossing the path of one of the most laborious species in the world –the leaf-cutter ants. There are 47 species leaf cutting ants. My first encounter with these ants came as no surprise in Costa Rica, where they seem to inhabit almost any land ecosystem except for high elevations above 6,500 feet. You may even find them carrying leaf pieces as you exit the airport terminal towards the parking lot where several trees make up the landscape.


The most interesting fact about leaf-cutters is their ability to farm their own produce- a fungus, to be exact. The pieces of leaves they collect are cut in smaller pieces before inoculating them with the fungus, the only source of food for the ants and their larvae. A well-established colony can contain over 5 million ants, of which most are females. The queen is about 2 inches in length and may live for over 20 years. During her lifespan, she can lay more than 200 million eggs.


These social arthropods are well known for their well-structured society divided into castes. The different castes are defined by size. The Mimims are the smaller workers helping to harvest the fungus and feed the larvae, while the Minors are found along the trails and are in charge of defending the workers from any intruders. The Mediae are larger and are responsible for collecting the leaves and bringing them inside the colony. Finally, the Majors are the largest of all, working as soldiers to protect the colony. They are also known for helping clear the paths used by the Mediae and getting rid of waste produced by the colony. Waste workers are usually left isolated from the fungus gardens to avoid contamination.


So, the next time you come across a trail of leaf-cutters, take your time to follow them, as you will be surprised at how far and large the colony may be. While these may be one of the toughest insects to shoot, you get plenty of opportunities as these guys will be on the move non-stop. Try them the next time to visit any country in Central or South America. There are two species that are found in the U.S. ; they can be found in Arizona, Texas and Southern California.


A mediae carrying a heart-shaped petal back to the colony. Costa Rica.
A mediae carrying a large leaf fragment and a protecting minor.
Leaf-cutters follow pheromone trails on their way to and from the foraging tree
Leaf-cutters live in underground colonies holding millions of ants.
The author and his wife at one large leaf-cutter colony in Costa Rica.
In 2022 we came across a nest colony that was over 35 feet wide. Here's Carolina Villegas posing on top of these massive nest for size reference.

Documenting Ophaga pumilio in Bocas del Toro, Panama.

I have a true passion for amphibians, those creatures with moist skin and sticky toes that many people fear or dislike. They are jumpy and at times hard to find, yet that’s nothing more than a challenging proposition to a frog fan like me. This time the trip took me for the second time in less than 6 months to the Bocas del Toro district in Panama. There’s something magical happening in this area composed of the mainland and few surrounding islands to the point that scientist called them the Galapagos of the Caribbean. By now you should know the importance of the Galapagos Islands and if you don’t here’s a tip. The Galapagos are a living evolution laboratory, where we can observe the effects of adaptive radiation, a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms. In the case of Bocas del Toro, a tiny frog has evolved many different phenotypes – a description of observable physical, physiological or behavioral characteristics that separate a group of individuals from the rest of the species. Different from genotypes which are the actual genetic identity, phenotypes are affected by both the genotype and the unique environmental conditions surrounding the individual. My subject is a tiny frog — Oophaga pumulio — a.k.a. the Strawberry Poison Dart Frog. In it’s most common form it looks like the one below.

A Strawberry Poison Dart Frog (Oophaga pumilio) carries her to tadpole to a water source, usually a bromelia.

The challenging part was finding these tiny frogs no more than one inch in length while dodging the weather. For starters, these guys don’t like bad weather. In order to find them I needed to hear them first. Too much rain and they go mute, making them nearly impossible to find on the leaf litter of the forest floor. Even when the conditions were optimal, they will choose impossible places from where to call, making them inaccessible or difficult to photograph. Walking through muddied trails, slipping down the hill sides or landing on large puddles of water made the adventure more exciting at times. Once found then I had to battle the elements and the gear. Constant drizzle and high humidity sabotaged the gear more than once. The copious sweat getting in the eyes and all over the cameras added to the miserable ground conditions. To visit some of the sites where these frogs can be found we had to take boats. One of the interesting things about these frogs is the fact that several phenotypes can be found in one same island. In the case of Isla Bastimentos there are at least three different forms of the frog. Isla Colon also have their share. Every large island in the Bocas del Toro archipelago offers at least two phenotypes. But the mainland offer a unique set of conditions that produced even more phenotypes. Geographical isolation by either rivers or mountains provided enough separation for the establishment of various morphs, occasionally only separated by a river and in places where two distinct population exist, you can even find some individuals sharing characteristics of both populations. Insane to think that such a small area produced so much color evolution, but considering these frogs have a tiny range and small number of offspring.  Below are some of the phenotypes I found during a three day expedition. 

But there’s more to these tiny frogs. Their aposematic coloration announcing their toxicity is just one of the traits that allow them to survive in the wild. Their reproduction is extremely complicated for a frog and I even show a high degree of parental care. The males attract the females by means of their calls. Once they find each other, they mate by means of a “cloacal kiss”. Soon after the female lays up to five eggs on a small puddle of water, usually collected on leaves on the forest floor. During this period the male urinates on the eggs to keep them moist if the water evaporates, and rotates the eggs before they turn into tadpoles. Ten to fourteen days later the tadpoles emerge from the eggs. At this point the female takes full care of the tadpoles. As the water dries out, she will carefully move the tadpoles to water filled vegetation usually bromeliads.  To prevent cannibalism among the tadpoles, the female deposits a single tadpole per section of the plant. The collected water is low in nutrient, so the female deposit unfertilized eggs to feed the tadpoles until they are ready to leave the water phase fifty days later.

Nothing more exciting than being able to document this species and its many phenotypes. But the work is not complete. There are many more phenotypes still to be documented. The adventure continues on a follow up expedition in 2022.