Document Type

Peer-Review Article


The daily and seasonal periodicities of drift of riffle beetles were examined in Polecat Creek. Illinois. during the spring and summer of 1978. Drift samples were collected from a single site over four 24-h periods. Dubiraphia vittata adults comprised 72% of the total numerical sample and exhibited greatest mean daily drift density in September. Macronychus glabratus adults were also common in drift collections, with highest densities re- corded during .'.lay and August. The drift of D. vittata and M. glabratus exhibited distinct patterns of die! periodicity with peaks occurring in the early hours of darkness. Substantial differences in drift densities between adult and larval stages were evident for D. vittata and M. glabratus. in both cases the adults were more prone to drift.

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Entomology Commons