The matching habitat choice hypothesis posits that individuals actively choose those microhabitats that best match their specificphenotype to maximize fitness. Despite the profound implications, matching habitat choice has not been unequivocally demonstrated. Weconducted two experiments to examine the impact of pigmentation pattern in the color polymorphic pygmy grasshopper Tetrix subulata onhabitat choice in a laboratory thermal mosaic arena. We found no behavioral differences in the thermal mosaic among pygmy grasshoppersbelonging to either pale, intermediate or dark natural color morphs. However, after manipulating the grasshoppers’ phenotype, the utilizationthrough time of warmer and colder parts of the arena was different for black-painted and white-painted individuals. White-paintedindividuals used warmer parts of the arena, at least during the initial stage of the experiment. We conclude that microhabitat choicerepresents a form of behavioural plasticity. Thus, even if the choice itself is flexible and not genetically determined, it can still lead to spatialgenetic structure in the population because the phenotypes themselves may be genetically mediated