The beetles in the air

Abstract

Flight activity and dispersal habits are still poorly known for most small Coleoptera species. Here, we investigate patterns of flight activity and flight altitude of beetles in the hemiboreal zone of northern Europe. Flying beetles were collected during one summer using four large suction traps mounted up to 93m above ground on a TV tower. The trapping site is situated in a mixed coniferous forest area subjected to standard logging practice in the province of Värmland, western Sweden. Altogether, 450 flying beetle species were collected in this rather ”trivial” habitat, representing about 20% of the provincial fauna and 10% of the entire Swedish beetle fauna. Rove beetles (Staphylinidae) comprised the most species rich family with 183 species. A total of over 47 700 individual beetles were caught. The catch was dominated by featherwing beetles (Ptiliidae) (over 40 000 individuals) among which Acrotrichis insularis (Mäklin, 1852) was by far the most numerous species. Staphylinidae comprised the second most individual-rich family (6.5%), whereas all other families together comprised less than 4% of the catch. Calculations of height - abundance distributions revealed that many beetles fly above the forest canopy. Our observations of density - height distributions in combination with the long species list suggest that a large segment of the forest beetle fauna is under constant flux.