ABSTRACT.1. 23275 arthropods collected by insecticide fogging from ten Bornean lowland rain forest trees were sorted to approximately 3000 species and assigned to guilds using two sets of criteria.2. The rank order for proportions of guilds of species but not individuals is similar in tropical and temperate canopy samples.3. Misplacement in the guild assignments of a few species can cause important differences in the proportions of certain guilds. This can seriously affect the results of comparisons of different samples, and views on proportional constancy of guilds of species on different trees.4. Guilds of arthropod species such as chewers, suckers, all phytophages, predators, ants and tourists, occur in constant proportions in samples from different tropical trees and this constancy of proportion is similar in samples from groups of‘closely related’and‘distantly related’trees.5. The guild concept of community structure and problems in assigning species to guilds are considered with respect to arthropod samples. The conclusions on constancy of proportion for guilds of species are tempered by remarks on the problems of guild comp