Canopy arthropods on dogwood,Cornus floridaL.; red maple,Acer rubrumL.; and yellow poplar,Liriodendron tulipiferaL., were bag-sampled during the day and night on six dates from July through September 1986 in the southern Appalachians of North Carolina. Diurnal and nocturnal comparisons were made for arthropod community composition and similarity. Overall numbers of canopy arthropod taxa were similar both between and within tree species, as was relative taxon abundance as assessed by community diversity measures. However, there were substantial differences in faunal composition and weighted arthropod numbers between daytime and nighttime canopies. Diel differences in canopy faunal composition is related to differential periods of activity among some canopy arthropods. These data suggest that canopy foliage may support greater densities and kinds of arthropods than those previously reported based on daytime sampling only. Experimental designs that include diel sampling would provide a more complete assessment of the structure and composition of canopy communities by taking into account the dynamic component of these communities.