Which mites are known to invade homes and attack humans after their primary host is removed?

• A. Demodex mites
• B. Ornithonyssus
• C. Sarcoptes
• D. Psoroptes

Answer: (B)

Ornithonyssus, commonly known as bird mites, are a type of mite that typically infest birds but may invade human dwellings once their primary host—birds—is removed or dies. After the birds leave, these mites can seek alternative hosts, which may include humans, leading to bites and discomfort. This behavior makes them particularly notable in the context of pest control in homes where birds may have nested and subsequently vacated.

Demodex mites are normally found on humans and do not invade homes from an external source. Sarcoptes is notable for causing scabies, a skin condition, but is not primarily associated with host removal in the context described. Psoroptes is typically related to animal infestations and doesn’t tend to enter human environments after the loss of their primary host in the same way that Ornithonyssus does. Thus, the unique behavior of Ornithonyssus makes it the correct choice in this scenario.