Rapid detection of red imported fire ant (Solenopsis invicta Buren; Hymenoptera: Formicidae) nests is important in assessing the control efforts and for monitoring dispersal of this pest. In this study, spectroscopic techniques were employed to characterize the reflectance spectra of fire ant nest soil and the areas surrounding the nests. The results showed significant differences between nest soil, grass, and bare soil not disturbed by fire ant at the 680 nm wavelength of the electromagnetic spectrum. The reflectance of nest soil was 10% to 15% lower than that of the surrounding non-nest bare soil at wavelengths of 780 to 1000 nm. Furthermore, the reflectance of nest soil was significantly correlated with soil water content (R² = 0.962).