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[Phthirus pubis]

Adult pubic lice (Phthirus pubis) measure 1.5-2.0 mm long and are dorsoventrally-flattened.  Adults are much broader in comparison to head and body lice.  The second and third legs have a large modified claw with a thumb-like projection, used for grasping on to hair shafts.  Nymphs resemble the adults but are smaller; there are three nymphal stages in the life cycle of P. pubis.  Adults and nymphs require human blood and are found only on the human host; although they are most-commonly found in the pubic and perianal regions, they may also be found on armpit, mustache, and chest hairs.

A	B

A: Adult female P. pubis.  An egg can be seen within her body cavity.
B: Adult male of P. pubis.

C	D

C: Three adult specimens of P. pubis on a hair shaft.
D: Nymph of P. pubis.