The common bedbug (Cimex lectularius) is the best adapted to human environments. It is found in temperate climates throughout the world and has been known since ancient times.

Other species include Cimex hemipterus, found in tropical regions (including Florida), which also infests poultry and bats, and Leptocimex boueti, found in the tropics of West Africa and South America, which infests bats and humans. Cimex pilosellus and C. pipistrella primarily infest bats, while Haematosiphon inodora, a species of North America, primarily infests poultry.

The rash may become secondarily infected; scratching the rash may break the skin and make secondary infection more likely. In persons with severely reduced immunity, such as those with HIV infection, or people being treated with immunosuppressive drugs like steroids, a widespread rash with thick scaling may result. This variety of scabies is called Norwegian scabies.

Scabies is frequently misdiagnosed as intense pruritus (itching of healthy skin) before papular eruptions form. Upon initial pruritus the burrows appear as small, barely noticeable bumps on the hands and may be slightly shiny and dark in color rather than red. Initially the itching may not exactly correlate to the location of these bumps. As the infestation progresses, these bumps become more red in color.

Generally diagnosis is made by finding burrows, which often may be difficult because they are scarce, because they are obscured by scratch marks, or by secondary dermatitis (unrelated skin irritation). If burrows are not found in the primary areas known to be affected, the entire skin surface of the body should be examined.

The suspicious area can be rubbed with ink from a fountain pen or alternately a topical tetracycline solution which will glow under a special light. The surface is then wiped off with an alcohol pad; if the person is infected with scabies, the characteristic zigzag or S pattern of the burrow across the skin will appear.

When a suspected burrow is found, diagnosis may be confirmed by microscopy of surface scrapings, which are placed on a slide in glycerol, mineral oil or immersion in oil and covered with a coverslip. Avoiding potassium hydroxide is necessary because it may dissolve fecal pellets. Positive diagnosis is made when the mite, ova, or fecal pellets are found.

Mites, together with ticks, belong to the subclass Acarina (also known as Acari) and the class Arachnida. Mites are among the most diverse and successful of all the invertebrate groups. They have exploited an incredible array of habitats, and because of their small size (some are microscopic) most go totally unnoticed. Many live freely in the soil or water, but there are also a large number of species that live as parasites on plants or animals and even some that feed on mold.

Some of the plant pests include the so called spider mites (family Tetranychidae), thread-footed mites (family Tarsonemidae), and the gall mites (family Eriophyidae). Among the species that attack animals are members of the Sarcoptic Mange mites (family Sarcoptidae), which burrow under the skin. Demodex mites (family Demodicoidea) are parasites that live in or near the hair follicles of mammals, including humans. Perhaps the best-known mite, though, is the house dust mite (family Pyroglyphidae).