Effect of trap height on abundance and species diversity of cerambycid beetles captured in forests of east-central Illinois

Trapping surveys that target wood-boring insects are usually deployed in the forest understory simply for convenience, but the abundance and species diversity of captured insects may be greatly influenced by the height of traps above the ground. Here, I assess how the vertical position of traps above the forest floor, and the type of trap bait, influence the abundance and diversity of cerambycid beetles that were captured in forested areas of east-central Illinois. Traps were set at three heights above the ground (~1.5 m in understory, ~6 m in lower canopy, ~12 m in the mid canopy), and were baited with either a fermenting bait or a blend of chemicals that were known pheromone components of cerambycids native to the study area. The twelve traps captured 845 cerambycid beetles of 49 species in the subfamilies Cerambycinae, Lamiinae, Lepturinae, Parandrinae, and the related Disteniidae. Adults of the cerambycine Eburia quadrigeminata (Say) were attracted by fermenting bait, and most were captured by traps at the highest position. Four species were attracted by the pheromone blend, including the cerambycines Phymatodes aereus (Newman), Phymatodes lengi (Joutel) and Xylotrechus colonus (F.), and the lamiine Astylidius parvus (LeConte). Most adult P. lengi were trapped in the mid canopy, whereas the remaining species were captured primarily in the understory. These findings suggest that trapping surveys of native communities of cerambycids, and quarantine monitoring for newly introduced exotic species, would be improved by including a variety of trap baits and distributing traps across vertical strata of forests