Document Type

Peer-Review Article


Five species of Brachycentrus and three species of Micrasema were collected. Previous records for Brachycentrus lateralis in Wisconsin are incorrect and should be for B. incanus. but B. lateralis larvae were collected recently in Douglas County. Brachycentrus americanus. B. numerosus. B. occidentalis, Micrasema kluane. M. rusticum and M. wataga usually occurred statewide in unpolluted permanent streams, but were generally absent from southern and eastern agricultural counties where most streams are organically enriched. More than one species and genus frequently occurred in the same stream. with Micrasema larvae often being found in streams with less current than required by Brachycentrus larvae. Larval cases of each species were usually distinctive in the last two instars. but there were variations due to habitat and ins tar. Brachycentrus americanus had a semivoltine life cycle in the northern half of Wisconsin and was univoltine in the south. Brachycentrus numerosus and B. occidentalis were always univoltine, but all Micrasema species had semivoltine populations and may be semivoltine in all Wisconsin streams.

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Entomology Commons