• Korean Journal of Ecology and Environment
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• v.38 no.spc
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• pp.17-21
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• 2005

We investigated the diel periodicity in the drift in relation to body size by field survey using the fourth instar grazing larvae of Micrasema quadriloba Martynov (Trichoptera, Brachycentridae) as a material. Although the larvae showed nocturnal drift periodicity, drift density in the nighttime was only twice that in the daytime. In both time periods, smaller individuals drifted significantly more, and the drift individuals in the daytime was the smallest in size (P< 0.05 in Sheffe's F). We discussed whether the drift of the fourth instar larvae drift behaviorally or accidentally considering larval size and food depletion.