Biting insects.
D000293:Adolescent; D000328:Adult; D002648:Child; D009033:Culicidae; D003888:Desensitization, Immunologic / Q000009:adverse effects; D004175:Diptera; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology*; D007299:Insect Bites and Stings / Q000150:complications* / Q000276:immunology; D008875:Middle Aged; D005423:Siphonaptera; D012882:Skin Tests; D014481:United States