Pentaclethra macroloba is a dominant canopy tree found in humid tropical forests from Honduras to Brazil, comprising 30-40% of all basal area at La Selva Biological Station, Costa Rica. To understand the full role that Pentaclethra macroloba plays in its surrounding environment I took a closer look into the interactions of the insects most abundant on P. macroloba; which include caterpillars, ants, and treehoppers. For a period of 2 months in La Selva Biological Station in Heredia, Costa Rica I observed and collected insects from P. macroloba saplings. To see what time the ants are most active on the plant as well as to see what species are most prevalent on P. macroloba, I looked at 38 saplings and conducted a census for ants at 4 times during the day: one in the early morning, one in the late morning/ afternoon, one at dusk, and one in the evening. The results clearly indicate that Crematogaster was the dominant ant species and were most active at 4:00pm when the sun was setting. In the treehopper experiment I visited a total of 5 stems that once had both treehoppers and ants and recorded the number of ants, number of treehoppers and recorded their behavior. The ants were often next to or on top of the treehoppers and the numbers of the treehoppers dwindled as the time passed, indicating that the treehoppers spent a period of time without moving from the particular P. macroloba stem and then dispersed. Lastly to study the herbivores of this canopy tree I collected a total of 31 caterpillars, 30 different species, found eating P. macroloba and reared them to adulthood to be identified. The information that I collected will be added to a database of known herbivores of P. macroloba. There are now six pinned specimens of the adults and one parasitoid in the insect collection. . The information collected gives insight into the variety of insects supported by this dominant canopy tree.