The University of Minnesota Insect Collection holds a rich collection of bees from Itasca State Park, MN, from 1937 and 1938. This collection formed the historical baseline data for comparison with a new survey conducted from 2011 to 2013, to measure changes in bee species over the last 75 yr. Bees were collected with timed net surveys and trap nests at eight different sites within the park. Megachilidae were the focal family for the current study, due to their importance as commercial pollinators and their unique nesting habits. Species richness and diversity of Megachilidae in the new survey were both significantly lower than that of the historical collection but were not significantly different when species accumulation curves were extrapolated to estimate the true species richness. Eleven species in the historical collection were not rediscovered, while three species not previously collected in Itasca State Park were found in 2011-2013.
- long-term change