Background/Question/Methods: Lepidopteran larvae (caterpillars) are important components of all terrestrial ecosystems where they play important roles as herbivores and food resources for predators and parasitoids. Along the Eastern Andes in Napo Province of Ecuador, the relationship between Passiflora species and host caterpillars was examined as a function of elevation. This sampling design was used to test the hypothesis that plant diversity and its associated lepidopteran fauna decrease with elevation. Several accessible altitudes ranging from tropical lowlands at ~500m to near-Páramo at ~3,000m were surveyed for plant diversity, presence of caterpillars and caterpillar eggs. For any given locale, using a standardized 10x10m diameter circular plot method, plants were collected and various measurements were taken. Also, caterpillars found living on the plants were individually bagged and tagged for rearing and identification purposes.

 The lack of species descriptions and basic natural history in this incredibly biodiverse region of the world is especially true for all taxa of insects. By better understanding how caterpillar and Passiflora diversity is affected by altitude we can get a better estimate of richness in the tropics for these and related organisms. Ultimately this can aid us in choosing regions in which reserve formation would make the biggest impact on conservation efforts. Results/Conclusions: Results indicated higher caterpillar and Passiflora diversity in the mid-level elevations rather than at the extremes. Plant abundances, considering either ramets or genets, also peaked at mid-elevations. This study shows that plant-herbivore network diversity does not monotically decrease with elevation, but rather peaks at intermediate elevations. These results also confirm that the mountainous regions of the South American tropics are home to an extremely high diversity of arthropods and plants and that mid-elevation sites of this region can be rightly considered of highest priority for focused conservation work.