Linnaeus described five species presently included in the genusTimarcha:Chrysomela goettingensis,Tenebrio caeruleus,Tenebrio laevigatus,Tenebrio latipes, andTenebrio rugosus. After a study of the relevant material, the identity of these species has been established. The following synonyms are proposed or confirmed:Timarcha goettingensis(Linnaeus, 1758) =T. latipes(Linnaeus, 1767),syn. nov.;Timarcha caerulea(Linnaeus, 1758),comb. nov.=T. balearicaGory, 1833,syn. nov.=T. balearicaPérez Arcas, 1865,syn. nov.;Timarcha rugosa(Linnaeus, 1767) =T. scabra(Olivier, 1807),syn. conf.=T. generosaErichson, 1841,syn. conf.;Timarcha laevigata(Linnaeus, 1767) =T. tenebricosa(Fabricius, 1775),syn. conf.. The type ofTenebrio caeruleusis a Chrysomelidae currently belonging to genusTimarchaand therefore can no longer be considered a Tenebrionidae (Helops caeruleus) nor the type species of genusHelops. For the sake of nomenclatural stability, an application to the International Commission on Zoological Nomenclature to change the relative precedence ofTimarcha caeruleaand retain usage ofT. balearicawill be made. An application to change the relative precedence ofTimarcha laevigatahas been submitted, which would lead to the conservation of usage ofT. tenebricosaas valid. Lectotypes are designated forChrysomela goettingensis,Tenebrio latipes,Tenebrio caeruleus,Timarcha balearicaGory,T. balearicaPérez Arcas,Tenebrio rugosus,Chrysomela scabra,Timarcha generosa,Tenebrio laevigatus, andChrysomela tenebricosa. For each of the valid species the diagnosis, distribution, and host-plant data are reported.