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Carabid beetles of the genus Cyphaloba, which live on dry savanna in East Africa, were investigated with respect to water balance, metabolism and regulation of body fluid solutes during dehydration. The beetles seemed to reduce their cuticular water permeability in the same manner as other dry habitat carabids and tenebrionids, but their high metabolic rates gave them relatively high rates of transpiratory wafer loss. The water loss appears to be limited by a substantial depression of the metabolism at daytime, when high temperatures and high vapor saturation deficit values in the air favor a high evaporative water loss. The basis of this depression is not clear, but it may in part be due to reduced physical activity. The beetles have high extracellular concentrations of sodium, but because evaporative dehydration causes the hemolymph volume to drop, sodium is removed from the hemolymph and deposited elsewhere in the body. A similar change takes place for free amino acids. (C) 1997 Elsevier Science Inc.