Formica obscuripes is a species of thatching ant that thrives in semi-arid regions of the Western United States. They create dome shaped mounds out of twigs and are common in the state of Utah. Overwintering nests of F. obscuripes contain adult workers only, with no brood, yet brood is present in the Spring before foraging commences. This suggests workers are storing fat, which they mobilize to make new workers in Spring. We measured fat storage throughout 2022's growing season, predicting an immediate decline in worker fat shortly after snowmelt and an increase in fat through the summer. We sampled 10 ants from each of 20 nests weekly, measuring wet weight, dry weight, and "lean" weight following the extraction of fat in hexane. Fat content was measured as dry weight minus lean weight, and water content as wet weight minus dry weight. Sampling occurred from the last week of April to the last week of October. Temporal dynamics of worker fat and water content were examined, with worker size and nests as covariates.