Relative effects of black, purple, and green multiple-funnel traps on catches of arboreal and saproxylic beetles in forest understoreys

Trap colour can be an important consideration in detection programmes for arboreal and saproxylic beetles. Green and purple intercept traps are more attractive than black intercept traps to the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive species in North America. In four experiments, I tested three commercial multiple-funnel traps (green, purple, and black), baited with various lure blends, to determine the relative effects of trap colour on catches of other bark and woodboring beetles, and their associated predator species, in north–central Georgia, United States of America. I captured numerous species of Cerambycidae (Coleoptera) (n = 51), Curculionidae (Coleoptera) (n = 33), and associated predators (Coleoptera) (n = 22) across the four experiments. However, the majority of the species captured were either unaffected by trap colour or were caught in greater numbers in black and purple traps than in green traps. The two exceptions were the predators Enoclerus ichneumonus (Fabricius) (Coleoptera: Cleridae) and Pycnomerus sulcicollis LeConte (Coleoptera: Zopheridae), which were more abundant in green traps than in black traps. Purple traps performed better than black traps for the following species: Cnestus mutilatus (Blandford) (Coleoptera: Curculionidae), Cossonus corticola Say (Coleoptera: Curculionidae), Xylobiops basilaris (Say) (Coleoptera: Bostrichidae), Buprestis lineata Fabricius (Coleoptera: Buprestidae), and Namunaria guttulata (LeConte) (Coleoptera: Zopheridae).