<p>Selection pressures exerted by ants on myrmecophilous caterpillars have led to the evolution of a diverse range of specialized structures, known as ant organs. Despite studies on the functional role of these ant organs in Lycaenidae, there is limited information on its functions in the sister family Riodinidae. Here, we first built an ethogram of the behavioral interactions between a facultative myrmecophilous riodinid caterpillar (<i>Synargis calyce</i>) and its most common attendant ants (<i>Camponotus crassus</i>). Second, we manipulated the functionality of two types of larval ant organs: tentacle nectary organs (TNOs) and anterior tentacle organs (ATOs) to determine their role in maintaining ant’s attendant behavior. We quantified the time and number of ants interacting with caterpillars across different treatments involving occlusion of TNOs and ATOs. The ethogram reveals that after the eversion of TNOs and ATOs by caterpillars, ants exhibit stereotyped behaviors, such as "jumping" over the caterpillar after ATO eversions. We found that the time and number of ants interacting with caterpillars were higher in the control group and the group with TNOs not occluded, followed by the group with functional ATOs. Caterpillars with both organs occluded received less attention. Our results indicate that the TNOs sustain ant-caterpillar interactions. There is a correlation between the eversion rate of ATOs and TNOs as observed in analogous tentacle organs of Lycaenidae species with similar type of trophobiotic ant-caterpillar interactions. We propose that interactions between <i>S. calyce</i> caterpillars and tending ants are mainly mediated by rewards offered from the TNOs and, to a lesser extent, by the eversion of ATOs.</p>