An insect sting is complicated by its introduction of venom, although not all stings are venomous. Bites, which can introduce saliva as well as additional pathogens and diseases, are often confused with stings. Specific components of venom are believed to give rise to an allergic reaction, which in turn produces skin lesions that may vary from a small itching weal, or slightly elevated area of the skin, to large areas of inflamed skin covered by vesicles and crusted lesions.