Recluse spider

The recluse spiders or brown spiders, genus Loxosceles (/lɒkˈsɒsɪliːz/), also known as fiddle-backs, violin spiders, or reapers, are a genus of venomous spiders known for their bite, which sometimes produces a characteristic set of symptoms known as loxoscelism. Recluse spiders are now identified as members of the family Sicariidae, having formerly been placed in their own family, the Loxoscelidae. Although recluse spiders have a bad reputation, they are usually not aggressive. Sicariidae are of the superfamily Scytodoidea. Other families in the Scytodoidea include Drymusidae, Scytodidae, and Periegopidae. Loxosceles is distributed nearly worldwide in warmer areas. All have six eyes arranged in three groups of two (dyads) and some are brownish with a darker brown characteristic violin marking on the cephalothorax. However, the 'violin marking' cannot be used as a reliable way to identify the spider as thousands of species of spider have similar markings. Spiders come with many markings varying greatly within the same species. Most Loxosceles can live for one and a half to two years. Many species of this genus can live for very long times without food or water.They are about 7–12 mm long. The most common and most famous species in the United States is the brown recluse spider (Loxosceles reclusa). It is found in a large area of the Midwest, west to Colorado and the New Mexico state line and east to northern Georgia. Sporadic records from other locations only represent incidental introductions, not established populations. The brown recluse feeds on whatever small prey is available, and has been observed to prefer scavenging over actively hunting. Other notable members of this genus include the Chilean recluse spider (L. laeta) and the Mediterranean recluse spider (L. rufescens). Recently, concerns have been raised regarding recluses spreading faster due to warmer air carrying them farther as a result of changing climate. On the contrary, newly hatched recluses do not travel via ballooning and thus the populations are confined to very tight spaces with dense populations. Loxosceles spiders, like Hexophthalma species, have potent tissue-destroying venoms containing the dermonecrotic agent, sphingomyelinase D, which is otherwise found only in a few pathogenic bacteria. Recent research has indicated the venom is composed largely of sulfated nucleosides, though these compounds are relatively new discoveries, so little is known about them. The venom produces necrotic lesions that are slow to heal and may require skin grafts. Rarely, the venom is carried by the bloodstream, causing red blood cell destruction. The venom is identical in male and female spiders, but females can have almost twice the concentration of toxins. For unknown reasons, the toxicity of the venom to mammalian species varies; recluse bites may cause necrosis in humans, rabbits, and guinea pigs, but not in mice or rats. The Chilean recluse (L. laeta) supposedly has a more potent venom, which results in systemic involvement more often. All Loxosceles species that have been tested have venoms similar to that of the brown recluse and all should be avoided. In general, though, they are not aggressive and commonly occupy human dwellings without causing problems.