How does a louse cough? - briefly
Lice have no lungs or airway structures, so they cannot produce a cough; any expulsion of particles occurs through bodily movements that dislodge debris.
How does a louse cough? - in detail
Lice are tiny, wingless insects that respire through a network of tracheae opening to the exterior via paired spiracles located on the thorax and abdomen. The tracheal tubes deliver oxygen directly to tissues, while carbon dioxide diffuses out through the same openings. Because the respiratory system lacks muscular structures analogous to a mammalian diaphragm, lice cannot generate the rapid, forceful expulsion of air that defines a cough.
When a louse encounters irritants such as dust, debris, or host secretions, it may perform a brief, localized contraction of the abdominal wall. This movement can dislodge particles from the spiracles, creating a short burst of airflow outward. The process involves:
- Activation of abdominal muscles that compress the hemocoel.
- Temporary increase in internal pressure within the tracheal trunks.
- Rapid opening of spiracular valves, allowing expelled material to exit.
The resulting airflow is modest, limited by the small diameter of the spiracles (typically 10–15 µm) and the low pressure differential achievable by the insect’s musculature. Consequently, the effect resembles a micro‑clearing action rather than a true cough.
Lice also rely on grooming behaviors—using their legs to brush the body and head—to remove contaminants that the brief abdominal contraction cannot expel. These mechanical actions, combined with the occasional pressure‑driven expulsion, constitute the only known mechanisms by which a louse can clear its respiratory openings.