How do you diagnose a bite or sting?

The annoyance of the mosquito or the immediate pain of the bee sting rarely poses a problem of recognition. Diagnostic problems arise when the arthropod is not seen or felt but leaves a nonspecific papular rash with redness, pain, itching, or swelling. A careful history, common knowledge of local arthropod populations, and a physical examination with a high index of suspicion is necessary. Arthropod bites may present with itchy, red papules in a particular distribution or pattern that suggests an area of potential arthropod exposure. For example, grouped bites around an exposed ankle suggest a nonflying arthropod such as a flea, mite, chigger mite, or bedbug. Mysterious bites are often secondary to a zoonotic source, which includes exposures to pets, pests such as rats and mice, and nesting birds or bats near the home or workplace. Consultation with a veterinarian or entomologist is extremely beneficial in unusual cases. A biopsy of the skin lesion often will show perivascular dermatitis with eosinophils.