Final answer:
One would expect to see a louse infesting human hair or clothing, such as the head louse on the scalp or the body louse on fabric, especially in historically unhygienic or crowded conditions.
Step-by-step explanation:
One place the speaker would expect to see a louse is infesting the hair or clothing of humans. Lice are parasitic insects that tend to reside where they have easy access to their food source, which is human blood.
The head louse (Pediculus humanus capitis), for instance, can be found on the human scalp, laying their eggs at the base of hair fibers.
Similarly, the body louse (Pediculus humanus corporis) tends to infest clothing, laying eggs on the fibers in the fabric. Historically, during times of poor hygiene, overcrowding, and in the tumultuous conditions of war, as during the Thirty Years' War, lice were a common issue and also vectors for diseases.