Vertical and temporal distribution of Coccinellidae (Coleoptera) in flight over an agricultural landscape

Twenty-one species of Coccinellidae were trapped in flight between 0.8 and 14.3 m from 1992 to 1995 in New Brunswick, Canada. Catches were larger at 0.8 m, with a rapidly decreasing capture rate leading, on average, to more than 50% of the catches at or below 3.8 m every year. The capture rate at 14.3 m was lower than at any of the nine other levels. Hippodamia convergens Guerin-Meneville flights were distributed close to the ground, with more than 50% of catches at 0.8 m, whereas Mulsantina hudsonica Casey flights were similar at all levels. The strong decreasing gradient of flight as a function of height for Coccinellidae (-0.825) was strongly influenced by that of H. convergens (-1.809) and of Coccinella septempunctata L. (-0.921) and Coccinella trifasciata perplexa Mulsant (-0.715). All other species had a slope of less than -0.5. The temporal distribution of flights was species specific, with maximum activity before the end of June for most, but this was not reflected in the frequency of catches for the entire family, which did not differ throughout the season, although they tended to be lower after mid-August. The weekly vertical flight distribution differed from the average distribution pattern only occasionally, probably during periods of long-distance dispersal. These profiles and known catches from a single trap location can be used to estimate dispersal activity at different heights.