Which ectoparasite is known for burrowing under the skin and causing scabies?

The itch mite is the correct answer because it is a microscopic ectoparasite scientifically known as Sarcoptes scabiei, which specifically burrows into the upper layer of the skin, leading to a condition known as scabies. Scabies is characterized by intense itching and a rash, primarily due to the body's allergic reaction to the mites and their waste. The life cycle of the itch mite involves burrowing under the skin to lay eggs, contributing to the spread of the infestation.

In contrast, head lice are external parasites that live on the scalp and feed on blood from the host's scalp, but they do not burrow into the skin. The common bed bug is another ectoparasite, but it feeds on blood and does not interact with the skin in the same manner as the itch mite—bed bugs live on the surface of the skin while they feed. Similarly, the oriental rat flea is known for being a vector for diseases and feeds on the blood of its host but does not burrow into the skin. Therefore, the unique behavior of the itch mite is what distinguishes it as the cause of scabies amongst these options.