1. Adult males and females of Gryllus campestris and Gryllus bimaculatus were kept at 3 and 5 constant temperatures respectively and at a fluctuating temperature for 3-4 weeks. The hemolymph and whole bodies of the treated crickets were analyzed for the osmotic pressure, contents of water, sodium, potassium, calcium and chloride and their main organic constituent, i.e. lipids, protein, free amino acids, total and low-molecular carbohydrates, polysacchardes, organic acids, nucleic acids and chitin. Males and females of Gryllus bimaculatus are characterized by the position of their hemolymph proteins in polyacrylamide electropherograms (Fig. 5). 2. The hemolymph in Gryllus campestris shows maximum osmotic pressure and maximum concentrations of all cations at 10°C. The concentration of total lipids, ninhydrin-positive substances and the freezing point depression of the body liquid in Gryllus bimaculatus are greatest at 5°C, whereas contents of aldoses and other carbohydrates are maximal at 13°C (Figs. 1-4). 3. Whole body analysis of Gryllus bimaculatus revealed highest concentrations of total lipids, total polysaccharides and ninhydrin-positive substances at 5°C, those of low-molecular carbohydrates and glycogen at 10°C. The lactate/pyruvate-ratio increases with decreasing temperature. The water content of these crickets is high at 27°C and low at 5°C; no essential differences were found in nucleic acids. The main storage substances seem to be lipid and polysaccharides (Figs. 6-13); an increase in lipids is correlated with a decrease in proteins. 4. The effects of a fluctuating temperature (+20°C/-1,5°C) on the inorganic and organic constituents of hemolymph and tissue are very different (Table 3). 5. Sex-dependent differences were demonstrated in the chemical composition of Gryllus at all temperatures. 6. The oxygen consumption is temperature dependent (Q 10≈2.5; Fig. 14).