The most important day of the year in Barichara, a colonial town in the Colombian Andes, is not Christmas, New Year or Easter, but what locals excitedly call La Salida, or “The Exit”.

When that day arrives, a palpable sense of anticipation surges through Barichara’s cobblestone streets and whitewashed buildings. Street sweepers and domestic cleaners throw down their tools mid-work, children sneak out of school and shopkeepers disappear without a trace.

They are all in search of the precious hormigas culonas, or “big-butt” ants, that are considered the caviar of Colombia’s north-central Santander region. Each spring as millions of these ample-bottomed insects hatch in the surrounding countryside, the annual harvest frenzy ensues.

“It’s first-come, first-serve,” said Margarita Higuera, a psychologist-turned-chef who moved to Barichara in 2000. “If you can get a bucket on top of an ant nest, then it is yours to keep no matter if you own the land or not.”

Taking place around March or April each year, when the sun shines brightly following days of heavy rainfall and the moon is full, La Salida marks the beginning of the ants’ annual mating season, which can last for up to two months, during which time locals scramble to collect as many queen ants as they can. Bloated with eggs and ready to reproduce, the brown, cockroach-sized queens are prized for their rotund, pea-shaped bottoms, which can taste like peanuts, popcorn or even crispy bacon when roasted and salted.

As well as being an excellent source of protein, the atta laevigata species, also known as the South American leafcutter ant, is a rich source of unsaturated fatty acids, which prevent high cholesterol. Other research published in the journal Frontiers in Nutrition has revealed that ants contain high levels of antioxidants and that regular consumption of them could help prevent cancer.

“That’s the reason why us baricharas (locals) usually live long, healthy lives,” said Cecilia González-Quintero, a shopkeeper who has been preserving and selling the ants in glass jars for 20 years. “The ants give us a special strength – [especially] the ones with the juicy culonas (big butts).”