Loxosceles reclusa (Brown Recluse)

About Loxosceles reclusa

Taxonomic Hierarchy

→ Kingdom: Animalia
→ Phylum: Arthropoda
→ Class: Arachnida
→ Order: Araneae
→ Family: Sicariidae
→ Genus: Loxosceles
→ Species: Loxosceles reclusa

Common Name (Official / AAS)

Brown Recluse

Other Common Names

Brown Spider, Violin Spider, Fiddleback

Author

Authors of species name: Willis Gertsch & Stanley Mulaik. First year published: 1940, as Loxosceles reclusus.

Pronunciation

locks-OSS-sell-eez reh-KLOO-suh

Meaning

In Greek, Loxosceles translates to “with slanting legs” (Cameron 2005). The species name, reclusa, is Latin for “removed” or “reclusive.”

Notable Previous Names

Loxosceles reclusus

Identifying Traits of Loxosceles reclusa

Size

Body length (excluding legs) of adult spider ranges from 7-12 mm; females average 9 mm, while males average 8 mm.

Female Primary Colors

Male Primary Colors

Eye diagram of Loxosceles reclusa

Eyes

Total of only six eyes, arranged in a triad of three pairs. This eye arrangement is one of the main diagnostic features for all Loxosceles species. Perhaps the only type of spider in North America with a similar eye arrangement is the “spitting spider” (family Scytodidae). However, their body shape is quite different from that of a “brown recluse.”

Legs

Legs long and slender in proportion to the body, especially so in males, and are light brown without any markings. The second pair is always the longest, while the third pair is the shortest. The leg posture can be somewhat “crab-like.” Tarsi (tips of legs) have 2 claws.

Body

Abdomen of both genders is an oval shape. Cephalothorax is flattened and widely pear-shaped. These spiders are very “leggy,” which may be your first observation. Abdomen is unmarked (no pattern) and can be pale yellow to dark reddish brown. Carapace is typically the same color as legs, but with a centrally located dark area that is broadest at the front and narrows to a point behind. The darkened shape is reminiscent of a violin or sometimes just a ‘Y’-shape. (Please note that the violin marking alone should not be used as the sole diagnostic feature. Many different kinds of innocuous spider also have the same marking!)

Range of Loxosceles reclusa

Loxosceles reclusa can be found in the following states, provinces and territories across the United States and Canada. Our current understanding of each spider's distribution is drawn from numerous scientific publications and online spider submissions, in order to be as accurate as possible. It is important to remember that spiders do not adhere to the territorial lines decided on by humans, therefore these ranges are subject to change.

Important Range Notes

The brown recluse may only live in a small portion of some of the states mentioned in the range; for example, only the very western portions of Virginia and North Carolina, not the entire states. Only the southeastern corner of New Mexico, southern half of Iowa, southernmost portion of Ohio, etc. Consult the red-colored area of UCR’s brown recluse range map for a rough outline. Reports of brown recluses outside of their known range are typically misidentifications or, rarely, specimens that have been accidentally transported via commerce.

United States

Canada

Species not seen in Canada.

Additional Information

Habitat

The “Brown recluse” is a nocturnal spider that prefers dark, dry, undisturbed crevices that it can fit snuggly into. Spots under the folded flaps of a cardboard box, within stacks of papers, behind loose baseboards, in piles of clothing, among closet debris, and behind bookcases are all potential “brown recluse” retreats. Within its native distribution, this species can also live outdoors under rocks, logs, or loosened tree bark. Though these spiders are not social (they do not share their webs or help each other catch food, etc), they are incredibly tolerant of one another and can be found in very high numbers within a single location. In fact, “where there is one, there are many” would typically be an accurate rule of thumb.

Web

This species is considered somewhat of a hunting spider and does not fully depend on a web to capture its prey. The retreat is lined with cotton-like, non-sticky threads that will alert the spider when a prey item becomes momentarily entangled. This gives the spider time to quickly lunge towards its struggling meal and inject venom, then back away to let the toxins take effect before beginning the feeding process.

Season

Mature specimens can typically be found at any time of year, especially indoors.

Food

Prey is any insect or other spider that the “brown recluse” is able to overcome.

Lifecycle

This species has an average lifespan of 1.5 – 2.5 years, but can live nearly twice that when kept in captivity and subjected to cooler temperatures each winter. The majority of mating and egg-laying takes place in June and July. A single female produces about 3 egg sacs in her lifetime, each filled with roughly 50 individual eggs (Vetter 2008). Some of the eggs may be infertile and some may be eaten by spiderlings from previous egg sacs, so only about half of them will actually end up hatching (Edwards 2001). Unlike many other kinds of spider, brown recluse spiderlings do not use ballooning as a method of dispersal, which is why their populations tend to be large and localized.

Remarks

This is a potentially dangerous species because its venom contains sphingomyelinase D, a necrosis-causing enzyme. Reactions to envenomation (bites) vary from “unremarkable” (little, if any, damage and self-healing) and “mild” (redness and itching, but usually self-healing) to “dermonecrotic” (a necrotic skin lesion that requires medical intervention) or, very rarely “systemic or viscerocutaneus” (affecting the vascular system and potentially fatal). The overwhelming majority of bites fall into the first two categories; less than 10% of bites fall into the more serious categories. Further, and most importantly, a great many other medical conditions can produce the necrotic skin lesions so often wrongly attributed to Loxosceles spiders. Please consult Rick Vetter’s 2008 article for a list of these. Misdiagnosis can lead to worse problems than a mere spider bite (if the actual cause is MRSA, for example). Lastly, the potential for bites is slim, and can be largely avoided by taking simple precautions.

There is a never-ending list of spider species (and even insects!) that are often mistaken for “brown recluses” by the general public. A couple of the top look-likes are the adult male “Southern House Spider” and “Longlegged Sac Spiders” (such as Cheiracanthium mildei), which are both types of spider that tend to be found in or around human habitations. They all have vastly different eye arrangements, though, so be sure to check. Perhaps the only spider that can be mistaken for a brown recluse based on the eyes alone, is the “spitting spider” (family Scytodidae), but they can typically be ruled out by other obvious physical features. In California, spiders in the family Tengellidae, and the species Metaltella simoni, are also frequently misidentified as brown recluses. Ask those with arachnological experience for help in identifying a suspected brown recluse. Keep in mind that medical professionals, the occasional pest control employee, and even entomologists have been known to misidentify these creatures! It is important to ask someone with knowledge and experience specific to arachnids.

Pictures of Loxosceles reclusa (Brown Recluse)

General

Female Spiders

Male Spiders

Filtering options are grayed out when we do not have pictures for the given perspective. If you are a spider photographer, you can submit pictures of spiders to help fill any voids in our ever expanding library.
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Dorsal
  • City/Region: Liberty
  • State: Missouri
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Attributes: Dorsal
  • State: Georgia
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Attributes: Dorsal
  • State: Georgia
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Attributes: Eyes
  • State: Georgia
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Dorsal
  • State: Florida
  • Country: United States
  • Loxosceles reclusa
  • Sex: MaleMale
  • Maturity: Adult
  • Attributes: Dorsal, Eyes
  • State: Oklahoma
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Dorsal
  • State: Kansas
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Eyes, Gravid
  • City/Region: Sapulpa
  • State: Oklahoma
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Eyes, Webs
  • City/Region: Sapulpa
  • State: Oklahoma
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Dorsal
  • City/Region: Sapulpa
  • State: Oklahoma
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Dorsal, Eyes, Gravid, Webs
  • City/Region: Sapulpa
  • State: Oklahoma
  • Country: United States
  • Loxosceles reclusa
  • Sex: MaleMale
  • Maturity: Adult
  • Attributes: Dorsal, Eyes
  • State: Oklahoma
  • Country: United States
  • Loxosceles reclusa
  • Sex: MaleMale
  • Maturity: Adult
  • Attributes: Dorsal, Eyes, Webs
  • State: Oklahoma
  • Country: United States
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Dorsal, Eyes
  • Loxosceles reclusa
  • Attributes: Dorsal
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Attributes: Dorsal, Eyes
  • Loxosceles reclusa
  • Sex: FemaleFemale
  • Maturity: Adult
  • Attributes: Dorsal, Webs

References and Further Reading

Various Research Papers

Scientific Diagrams and Keys for Identification

References for the Casual Reader

Species guide last updated: February 18, 2014

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