brown recluse spider, a small poisonous arachnid, Loxosceles reclusa, also known as the brown or violin spider, found in both North and South America. The bite produces a characteristic necrotic lesion. The venom from its bite usually creates a blister surrounded by concentric white and red circles. This so-called bull’s-eye appearance is helpful in distinguishing it from other spider bites. There is little or no initial pain, but localized pain develops in about an hour. The patient may experience systemic symptoms; nausea, fever, and chills are common, but the reaction is usually self-limited. Immediate treatment includes keeping the victim quiet and immobilizing the bite area at the level of the heart. A bleb forms, sometimes in a target or bull’s-eye pattern. The blood-filled bleb increases in size and eventually ruptures, leaving a black scar. Antivenin is not available in the United States or Canada.
