Abstract
Life cycles of 27 caddisfly species were estimated from weekly adult flight periodicity data during 2010-2014 from a forest and a meadow site of a small stream in northern Lower Michigan. Of the 11 species abundant only at the forest site, 10 appeared to be univoltine and 1 appeared bivoltine. Of the 13 species abundant only at the meadow site, 5 appeared univoltine, 5 appeared bivoltine, and 3 were enigmatic due to inconsistent flight peaks between years. Although the sites were separated by ∼400 m, only three species were abundant at both sites due to differences in stream habitat and food availability. Two of these species had notably dissimilar life cycles between sites, reflecting these differences. Despite the study dates encompassing both the warmest and coldest years of the 2000s, most species retained consistent flight periods between years. This consistency with date appeared unrelated to lunar phase. Date was a better predictor of flight periodicity than water temperature for every species except those that emerged earliest in the season. Warming water temperatures appeared to synchronize emergence of species at the meadow site to a greater degree than those of the forest site, probably due to the greater range of temperatures at the meadow site, although date was still the better predictor at both sites. These data suggest that warming water temperatures, although important under certain conditions, may not always be primary life cycle synchronizers in small streams.