Fly Fecal Pellet
Transmitted Oblique Cross Polarized Light and Reflected Darkfield Illumination
Significance in the Environment:
Insect, spider, and mite fecal material contains highly birefringent nitrogen containing compounds.
The dominant compound is guanine. A variety of other compounds are present, which includes those specific
agents responsible for any allergic reactions to each species. The guanine is evident here as the
bright spots in the otherwise dark deposit.