Pubic Lice Activity Patterns: Nocturnal Feeding and Light Preference

Pubic lice are obligate hematophages that feed every 4–6 hours, day and night. They do not have a true circadian rhythm but show behavioral preferences:

• Feeding: Continuous; host immobility during sleep may facilitate feeding.
• Light avoidance: Photophobic—prefer dark, warm environments (pubic hair). Bright light causes dispersal.
• Movement: Slow crawl (1–2 cm/min); cannot jump or fly.

Clinical Implications

• Itching often worse at night due to increased feeding activity on stationary host and fewer distractions.
• Examination under bright light may cause lice to move away from inspection site—use magnifier with directed light.
• No evidence they "prefer dim night lights"; they simply avoid bright light.

Understanding behavior aids detection and explains symptom timing.