How to distinguish dead lice from live ones? - briefly
Live lice move when touched, have a clear, glossy body, and show a faint, intact abdomen; dead lice remain motionless, appear dull‑gray, and their abdomen often collapses or appears fragmented. Checking for movement and body sheen quickly separates the two.
How to distinguish dead lice from live ones? - in detail
When examining a head for infestation, determine the status of each specimen by observing several key characteristics.
First, visual inspection under adequate lighting reveals movement. Live insects exhibit spontaneous locomotion, shifting legs, antennae, or body orientation within seconds. In contrast, a lifeless specimen remains completely still, even when the host’s hair is gently brushed or the scalp is tapped.
Second, coloration provides clues. Living lice retain a translucent to brownish hue, with clear internal structures visible through the cuticle. Dead individuals often appear darker, with a loss of translucency and a dull, matte surface. Occasionally, a faint brown residue accumulates around the abdomen of a deceased louse.
Third, posture distinguishes the two states. Live lice cling tightly to hair shafts, their claws gripping firmly and their bodies aligned with the hair’s direction. A dead louse may fall off the strand, lie flat on the scalp, or assume an unnatural, curled position. If the insect is found detached and lying motionless on a surface, it is almost certainly deceased.
Fourth, tactile response can be tested carefully. Using a fine-toothed comb, gently pull a suspected specimen. A living louse will resist, attempting to cling with its claws, whereas a dead one will slide off without resistance.
Fifth, microscopic examination offers definitive confirmation. Under low magnification (10–40×), live lice display rhythmic leg movements and a clear, intact respiratory system. A dead specimen shows collapsed tracheae, rigid limbs, and sometimes internal discoloration.
Finally, consider the presence of nits. Viable eggs are firmly attached to the hair shaft near the scalp and are typically found alongside live lice. Empty shells (nits that have hatched) are lighter, more translucent, and often accompany dead insects.
Practical checklist for identification
- Observe for spontaneous movement within 5 seconds.
- Assess coloration: translucent vs. dull, darkened.
- Examine posture: clinging vs. detached, curled.
- Perform a gentle pull test with a comb; note resistance.
- Use magnification to check for leg motion and respiratory integrity.
- Verify associated nits: live lice often coexist with viable eggs.
Applying these criteria systematically enables accurate discrimination between living and deceased lice, facilitating appropriate treatment decisions.