Which of the following is NOT an external parasite?

• A. Louse
• B. Ascarid
• C. Mite
• D. Tick

Answer: (B)

The key idea is telling where a parasite spends most of its life. External parasites live on the animal’s body—on the skin or in the fur or coat—feeding from the outside. Lice, mites that live on the skin, and ticks that attach to the skin are classic examples of these ectoparasites. In contrast, ascarids are roundworms that inhabit the animal’s internal organs, primarily the digestive tract, making them internal parasites (endoparasites). Because their main habitat is inside the body rather than on the surface, they are not considered external parasites.