Other Common Names
Violin or Fiddleback Spiders
Recluse spiders
Explanation of Names
Loxosceles is from a two-ending Greek adjective meaning 'with slanting legs'. The presumably refers to the fact the legs are slighly laterigrade. Cameron(2005)
(1)
Violin or Fiddleback Spiders because some species have a violin-like mark on the top of the cephalothorax.
Recluse spiders because of their shy nature.
Numbers
There are 11 native species found in the United States:
Loxosceles apachea
L. arizonica
L. blanda
L. deserta
L. devia
L. kaiba
L. martha
L. palma
L. reclusa
L. russelli
L. sabina
There are two species of brown spider that are occasionally introduced into the U.S., Loxosceles laeta and Loxosceles rufescens
Identification
Most are brownish or yellowish. They have six eyes in three pairs (
This image shows the eye arrangement of brown spiders) The top of the cephalothorax is rather flat and has a lengthwise furrow along the midline at the rear third. Each foot has two claws.
Range
In the US:
Brown spiders are occasionally transported outside of their range on or in furniture, boxes, and plants.
Habitat
These spiders spin small, irregular webs underneath bark and stones.
Brown spiders are nocturnal, therefore most likely encountered at night when they are foraging for food. During the day they hide in secluded places.
Remarks
Brown spiders will not bite unless provoked.
Little is known about the venom and bite of the lesser-known species of brown spiders.
“Although there are suspected variations in virulence among the species, all Loxosceles spiders should be considered potentially capable of producing dermonecrosis to some extent.” (Arachnids Submitted as Suspected Brown Recluse Spiders (Araneae: Sicariidae): Loxosceles Spiders Are Virtually Restricted to Their Known Distributions but Are Perceived to Exist Throughout the United States by Rick Vetter)
Loxosceles venom is cytotoxic to humans.
(1) Internet References
http://www.xs4all.nl/~ednieuw/Spiders/Agelenidae/BennettVetterCFP.pdf -
An Approach to Spider Bites: Erroneous Attribution of Dermonecrotic Lesions to Brown Recluse or Hobo Spider Bites in Canada: Rick Vetter, MSc. and Robert Bennett, MSc, Ph.D. An interesting article (PDF format) about necrotic spider bites, their frequency of occurrence, and the frequency of misdiagnosis. Although this deals with Canadian data, it is very insightful about necrotic spider bites in the US also.
