We measured the degree of adaptation to a xeric environment of immatures and adults of the striped earwig,Labidura riparia(Pallas). All stages of the striped earwig were moderately tolerant to heat, with critical thermal maxima ranging from 45.2 to 46.1°C for small and large nymphs, respectively. Percentage body water content ranged from 58.9% for females to 75.6% for small nymphs. Cuticular permeabilities were similar for all stages and were within the range of those reported for xeric species, ranging from 8.5 μg water lost per cm2·h·mm Hg for medium-sized nymphs to 17.0 μg water lost per cm2·h·mm Hg for females. Percentage total body water lost increased linearly with desiccation time. Lethal body water loss varied among stages and ranged from 47.6 to 52.9% for small and medium nymphs. The mean hour of death ranged from 16.8 h for small nymphs to 70.7 h for large nymphs, indicating that small nymphs were the least tolerant of desiccating conditions.