On December 25, 1995 Costa Rica issued a minisheet of four different rouletted stamps as an "America UPAEP" issue with the theme of sustainable development. Two of the stamps in this sheet depict landscapes, and two show native fauna, including this 50 colones value depicting leafcutter ants (Atta cephalotes).
From wikipedia, "Atta cephalotes is a species of leafcutter ant in the tribe Attini (the fungus-growing ants). A single colony of ants can contain up to 5 million members...The colony comprises different castes, known as "task partitioning" and each caste has a different job to do...A special cast of workers manages the colony's rubbish dump. These ants are excluded from the rest of the colony. If any wander outside the dump, the other ants will kill them or force them back. Rubbish workers are often contaminated with disease and toxins, and live only half as long as their peers."