Population characteristics of the desert isopod H. reaumuri and its energy allocation during each penophase were investigated in the Negev desert, Israel. It was found that on the individual level, 52% of the energy is allocated to the prereproductive, and 48% to the reproductive phenophases. On the population level, only 10-23% is devoted to isopods which are involved in reproduction. Assuming that the energy allocation pattern in H. reaumuri is the consequence of its life history strategy, two unique evolutionary lines were suggested. One suggestion is the evolution of the family mode of life which increases the probability of the individual's survival. This is due to parental investment and co-operation between siblings. The other suggestion is the evolution of high energy utilization for burrowing, in order to solve the low and unpredictable nature of water resources in the desert.