Using ultraviolet light traps, over 5000 caddisfly specimens were collected from a forest and a meadow habitat of Fairbanks Creek in northern Lower Michigan. Samples were collected every 15 minutes, interspersed with 15 minutes of no sampling, from sunset to sunrise during 5 nights from late June to mid-July 2014. Despite having fundamentally different caddisfly assemblages dominated by different species, mean specimen abundance and mean species richness in both habitats exhibited similar trends: peaking between 22:30 and 23:00, decreasing until 02:00 or 02:30, increasing again slightly during the later morning periods, and then decreasing to near zero by 06:00. On average, \u3e90% of species from the forest site were caught by 00:00 and 100% by 02:00, whereas meadow site richness didn’t reach 90% until 01:00 and 100% until 05:00. Species richness per night correlated strongly with dew point for both sites, reflecting consistently warm temperatures throughout the sampling period. Our results suggest that caddisfly flight is controlled by both innate behavior and environmental factors like temperature, and that sampling should continue late into the night to maximize capture, especially in open-canopied areas
