A spider bite is an injury resulting from the bites of spiders or other closely related arachnids.
Spiders are active hunters and rely heavily on their bites to paralyze and kill their prey before consuming it. They also bite in self-defense. While many spiders will never attack animals larger than themselves, some—e.g., Atrax robustus—exhibit a rather aggressive behavior and will stand their ground when approached by larger animals. Most spider bites occur when humans unintentionally press up against spiders and receive a defensive bite. On rare occasions, spiders may make prey mistakes and bite a human finger or other body part as though it were a caterpillar or other such insect.
The hobo spider (Tegenaria agrestis) is a member of the genus of spiders known colloquially as funnel web spiders, but not to be confused with the Australian funnel-web spider. It is one of a small number of spiders whose bites are generally considered to be medically significant. Individuals construct a funnel-shaped structure of silk sheeting and lie in wait at the small end of the funnel for prey insects to blunder onto their webs. Hobo spiders sometimes build their webs in or around human habitations.
The brown recluse spider or violin spider, Loxosceles reclusa, Sicariidae (formerly placed in a family "Loxoscelidae") is a spider with a venomous bite.
Brown recluse spiders are usually between 6–20 mm (1⁄4 in and 3⁄4 in), but may grow larger. While typically light to medium brown, they range in color from cream-colored to dark brown or blackish gray. The cephalothorax and abdomen may not necessarily be the same color. These spiders usually have markings on the dorsal side of their cephalothorax, with a black line coming from it that looks like a violin with the neck of the violin pointing to the rear of the spider, resulting in the nicknames fiddleback spider, brown fiddler, or violin spider.
Phoneutria, commonly known as Brazilian wandering spiders, armed spiders ("armadeiras", as they are known in Portuguese), or banana spiders (not to be confused with the relatively harmless Nephila), are a genus of aggressive and venomous spiders of potential medical significance to humans. They are mainly found in tropical South America, with one species in Central America. These spiders are members of the Ctenidae family of wandering spiders.