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Bites of recluse spiders

Richard S Vetter, MS
David L Swanson, MD
Section Editors
Daniel F Danzl, MD
Stephen J Traub, MD
Deputy Editor
James F Wiley, II, MD, MPH


The entomology of recluse spiders (Genus Loxosceles) and the clinical manifestations, diagnosis, differential diagnosis, and management of their bites will be reviewed here.

An overview of spider bites and the management of bites of other spiders are discussed separately. (See "Approach to the patient with a suspected spider bite: An overview".)


Spiders of the genus Loxosceles are known colloquially as recluse spiders, violin spiders, fiddleback spiders, and in South America, by the nonspecific name "brown spiders." These terms are used when describing multiple Loxosceles species as a group. When the common name "brown recluse spider" is used here, it refers only to the one species, L. reclusa, which is widespread and commonly found in homes in the indigenous Central Midwestern United States.

Loxosceles spiders have gained notoriety in the medical literature and lay press because their bites sometimes become necrotic [1,2]. However, this is a relatively uncommon sequela, and is largely limited to areas of the United States where these spiders are endemic (figure 1). Outside of these regions, the vast majority of necrotic skin lesions are caused by other disorders [3-6]. (See 'Differential diagnosis' below.)

Appearance and identification — Recluse spiders are rather nondescript brown spiders (picture 1 and picture 2). The most accurate method of identifying a recluse spider involves counting the eyes. Most spiders have eight eyes in two rows of four. In contrast, recluse spiders have six eyes, with a pair in front, a pair on both sides, and a gap between the pairs (picture 3). With the naked eye or low magnification, the eye pairs (dyads) may appear as individual eyespots.

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Literature review current through: Oct 2017. | This topic last updated: May 31, 2017.
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