Relative abundance of day-flying insects in treefall gaps vs shaded understory in a neotropical forest

Day-flying insects were sampled in treefall gaps and closed understory within the semideciduous, lowland forest of Barro Colorado Island, Panama, from April (late dry season) to August (mid wet season) in 1980. Transparent strips of plastic coated with tanglefoot were suspended above ground at 5 treefall and 5 understory sites. Traps were "run" from early morning to late afternoon for 4-day periods at approximately 2-wk intervals. For most taxa, the numbers of individuals captured were relatively low during the first sampling period (prior to the onset of heavy rains), increased to peak levels between mid-May and mid-June, and then declined slightly in July and August. Statistically significant differences in abundance between gap and understory sites were noted only for Formicidae, Coleoptera, and Psocoptera. In all 3 cases, greater numbers of individuals were trapped at understory sites. Size frequency distributions were similar between treefall gaps and understory for all taxa.