How big was the lice in World War 1?

During World War I, lice were a significant problem for soldiers, particularly in the trenches. The most common type, the body louse (Pediculus humanus corporis), could grow up to 2 mm in size. These lice thrived in the unsanitary conditions of war, causing discomfort and contributing to the spread of diseases like trench fever. Efforts to combat lice included delousing stations and the use of insecticides, but infestations remained a persistent issue throughout the conflict.