Loxosceles

Loxosceles is a genus of spiders commonly known as recluse spiders or violin spiders. They are members of the family Sicariidae, which also includes the six-eyed sand spiders. Loxosceles species are found worldwide, with a significant number of species native to the Americas. The most well-known member of this genus is the brown recluse spider (Loxosceles reclusa), which is infamous for its necrotic venom.

Description

Loxosceles spiders are medium-sized, with a body length ranging from 6 to 20 mm. They are characterized by their six eyes arranged in three pairs (dyads) in a semicircle, unlike most spiders which have eight eyes. The cephalothorax and abdomen are typically brownish, with the cephalothorax often having a darker violin-shaped marking, which is why they are sometimes called violin spiders.

Habitat

These spiders prefer warm, dry environments and are often found in undisturbed areas such as attics, basements, and woodpiles. They are nocturnal hunters, feeding on small insects and other arthropods.

Venom

The venom of Loxosceles spiders contains a complex mixture of enzymes, including sphingomyelinase D, which is responsible for the necrotic lesions associated with their bites. The severity of a bite can vary, ranging from mild irritation to severe necrosis and systemic symptoms. Not all bites result in significant envenomation, and many heal without medical intervention.

Medical Significance

Bites from Loxosceles spiders can cause a condition known as loxoscelism, characterized by local necrosis and, in some cases, systemic symptoms such as fever, chills, and hemolysis. Treatment is primarily supportive, focusing on wound care and pain management. In severe cases, surgical intervention may be necessary to remove necrotic tissue.

Prevention

Preventing bites involves reducing contact with these spiders by keeping living areas clean and clutter-free, sealing cracks and crevices, and using insecticides if necessary. Wearing gloves and long sleeves when handling firewood or cleaning storage areas can also reduce the risk of bites.

Also see

• Brown recluse spider
• Spider bite
• Necrotizing fasciitis
• Arachnid
• Venom