Phthira

Phthira is an obsolete term used in older medical and entomological texts to refer to lice, particularly those infesting humans. It encompassed various types of lice, including head lice ( Pediculus humanus capitis), body lice (Pediculus humanus humanus), and pubic lice (Pthirus pubis - note the similar spelling).

The term "Phthira" is derived from the Ancient Greek word φθείρ (phtheir), meaning louse. As scientific nomenclature evolved, "Phthira" was superseded by more specific and accurate classifications based on detailed morphological and genetic analysis. Modern scientific usage favors the genus names Pediculus and Pthirus to distinguish between different species of human lice.

The term might still occasionally appear in historical texts or older medical literature, and understanding its historical usage is useful for interpreting these resources. However, it is no longer considered an appropriate or accurate term in contemporary scientific or medical contexts. The specific type of louse should always be identified when discussing or documenting infestations.