Commercial farmers and hobbyist gardeners hate bachac with a passion. They have been known to strip entire orchards or kitchen gardens overnight like a swarm of nocturnal locusts, leaving behind just twigs and naked trees in their wake.
Hate them or not, you must admit they are indeed hardworking animals. The bachac can be found from the southern United States all the way down to the tip of South America. In these parts, the bachac is known by the obvious name leafcutter ant or leaf chewing ants. Surprisingly, there are 47 different species of these ants of which only two inhabit Trinidad and Tobago.
Bachac in Trinidad and Tobago
The two species of bachac found in Trinidad and Tobago are Atta Cephalotes and Acromyrmex Octospinosus. Atta Cephalotes or Forest Bachac has a shiny appearance, is reddish-brown and has long slender legs. These ants have three pairs of spines and a smooth exoskeleton on the upper surface of the thorax.
Acromyrmex Octospinosus vary in colour from brown to almost black and the legs are short compared with those of the previous species. They nests in various habitats including walls, under stones, under fallen tree trunks and in the ground itself. They has four pairs of spines and a rough exoskeleton.
The fungus farmers
One interesting thing you should know about the bachac is they don’t actually eat leaves, instead they use the leaf cuttings as a food for a fungus. This fungus is found nowhere else but in bachac colonies. That is correct, the bachac is actually fungus farmers. Every different species of bachac farm a different species of fungus, however, they are members of the family Lepiotaceae.
Colony second to human societies
Bachac colonies in terms of complexity is second only to human societies. In a few years, the central mound of their underground nests can grow to more than 30 m (98 ft) across with smaller radiating mounds. This can extend out to a radius of 80 m (260 ft) taking up 30 to 600 m2 (320 to 6,460 sq ft) and containing eight million individuals.
The four-caste bachac colony
There is a clear hierarchy within these colonies. Like all ant colonies, there is a queen and there are four castes being present in established colonies—minims, minors, mediae, and majors.
Minims are the smallest workers and tend to the growing brood or care for the fungus gardens. You generally don’t see them walking on the ground as they rarely leave the colony.
Minors are slightly larger than minims and are present in large numbers. They are the first line of defense and continuously patrol the surrounding terrain. They vigorously attack any enemies that pose a threat.
Mediae are the generalised foragers which cut leaves and bring the leaf fragments back to the nest.
Majors, the largest worker ants, act as soldiers defending the nest from intruders. The largest soldiers, Atta laevigata, participate in other activities such as clearing the main foraging trails of large debris and carrying bulky items back to the nest.
When next you observe a trail of bachac, remember that they may seem as pests but they are hard working farmers too.
January 2018 www.sweettntmagazine.com
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