Effects of trap height on captures of arboreal insects in pine stands of northeastern United States of America

Knowledge of the effects of variables that can influence trapping results should help to optimise efforts in exotic species detection and other surveys. Two vertical trap placements (understorey, canopy) were tested to determine influence of these two heights on captures of Scolytinae (Coleoptera: Curculionidae), Cerambycidae (Coleoptera), and Siricidae (Hymenoptera) using semiochemical-baited multiple-funnel traps. Traps were baited with -pinene, ethanol, ipsdienol, and ipsenol. A total of 8463 insects from 65 species and one genus were captured during the study. Average species richness, species diversity, abundance, number of unique species, and expected diversity were higher in understorey compared with canopy traps. Jaccard (0.94 0.05) and SOrensen abundance (0.97 +/- 0.03) similarity indices suggested highly similar communities sampled at the two trap heights. Dendroctonus valens LeConte, Dryocoetes autographus Ratzeburg, Hylastes opacus Erichson, Orthotomicus caelatus (Eichhoff), Gnathotrichus materiarius (Fitch), Asemum striatum (Linnaeus), Monochamus scutellatus scutellatus (Say), Rhagium inquisitor (Linnaeus), and Xylotrechus sagitattus sagitattus (Germar) were more abundant in understorey traps. In contrast, Ips pini (Say), Pityogenes hopkinsi Swaine, Monochamus carolinensis (Olivier), Acmaeops proteus (Kirby), and Astylopsis sexgutatta (Say) were more abundant in canopy traps. The common practice of trapping in the understorey may be optimal for sampling arboreal insects as part of survey efforts. However, additional species may be found by trapping at other vertical placements.