An arthropod bite or sting is a localized inflammatory reaction that develops in response to the bite or sting and is manifested by localized swelling and redness. Bites and stings can occur in patients of any age. Pain, burning, and itching are common symptoms.

Arthropods include insects (stinging or venomous hymenoptera [bees, wasps, fire ants] and non-venomous insects [mosquitoes, chiggers, fleas, etc]) as well as ticks, mites, spiders, scabies, and body lice.

Arthropods may transmit human illness (tick fever, Lyme disease, Rocky Mountain spotted fever, a variety of encephalitides, malaria, etc) and venomous bites may trigger systemic allergic reactions, including anaphylaxis.

In contrast to cellulitis, bites and stings are often multifocal and may be bilateral. There may be a visible punctum, and the patient may have a recollection of insect exposure. There may be concomitant cellulitis, however, as bites and stings often serve as an important nidus of infection.