Another species, F. femoralis (Stein) is frequently encountered in animal manure, and the larvae resemble those of scalaris and canicularis.

However, the larvae of F. femoralis have lateral posterior processes which are intermediate in branching and length of the terminal portion, in comparison to scalaris and canicularis.

To further complicate larval identification, it is extremely difficult to distinguish F. femoralis from F. pusio (Weidemann) which may occur, but is fortunately less common in animal facilities.

The adults of F. femoralis and F. pusio are mostly black, and much smaller than F. canicularis and F. scalaris. They are therefore easily distinguished in the adult stage.

Although F.canicularis is, overall, the most common Fannia in confined animal operations, it is important to be sure that it is the species present in the manure in a particular situation.