Brown Recluse

• It has six eyes arranged in three pairs rather than the eight of most spiders: one of the most reliable features for identifying it.
• It almost always bites by accident, when it gets trapped against the skin while someone is dressing or reaching into a box.
• Far more recluse bites have been diagnosed than the species' actual distribution allows: a good share of them are in fact bacterial infections.
• It is identified by a violin-shaped marking on the cephalothorax and, above all, by its eyes: it has six instead of eight, arranged in three pairs, a far more reliable feature than the violin.
• Its venom contains phospholipases D, formerly known generically as sphingomyelinase D, which destroy cell membranes and cause the characteristic necrosis.
• But the main problem with this species is overdiagnosis. Outside its real range, in the south-central United States, it is constantly blamed for necrotic lesions that have some other cause, and in states such as California this has reached the status of urban legend.
• And that mistake has medical consequences: many of those lesions are in fact MRSA infections or other diseases, and treating them as a spider bite delays the correct diagnosis.
• Most verified bites cause no necrosis: they amount to redness and itching and heal on their own.
• Surgically excising the bite area to prevent necrosis is contraindicated and usually worsens the outcome.
• It is retiring and bites only when trapped against the skin, typically while getting dressed or getting into bed.

Skeleton type

Invertebrate - chitin exoskeleton (arachnid)

Habitat and environment

Corners, storerooms, boxes and dry cavities of houses in the central and southern United States

Sources consulted: Wikipedia (es): Loxosceles reclusa

The pins mark the parks where its presence is documented.