|Latrodectus hesperus female|
Chamberlin & Ivie, 1935
Latrodectus hesperus, the western black widow spider or western widow, is a venomous spider species found in western regions of North America. The female's body is 14–16 mm (1/2 in) in length and is black, often with an hourglass-shaped red mark on the lower abdomen. This "hourglass" mark can be yellow, and on rare occasions, white. The male of the species is around half this length and generally a tan color with lighter striping on the abdomen. The population was previously described as a subspecies of Latrodectus mactans and it is closely related to the northern species Latrodectus variolus. The species, as with others of the genus, build irregular or "messy" webs: Unlike the spiral webs or the tunnel-shaped webs of other spiders, the strands of a Latrodectus web have no apparent organization. Female black widows have potent venom composed of neurotoxins. Fatalities usually only happen with children and the elderly, however medical treatment may be required for others as well. However, the male black widow is harmless to humans. The female's consumption of the male after courtship, a cannibalistic and suicidal behaviour observed in Latrodectus hasseltii (Australia's redback), is rare in this species. Male western widows may breed several times during their relatively short lifespans. Males are known to show preference for mating with well-fed females over starved ones, taking cues from the females' webs.
The latrodectus Hesperus can be found in western regions of North America.
Female stimulates by contact with male webs Male and female Hesperus produce sexually specific scents which are combined with their silk; each sex responds by initiating mating when it comes in contact with a web of the opposite sex.
Lactrodectus Hesperus frequently hangs upside down near center of the web and waits for any insects to enter the web to attack. It bites its victim then wraps it in silk.
Lactrodectus Hesperus has few parasites known to affect them; one is the wasp.
Interactions With Humans
They may often live in human dwellings, usually in cluttered dark areas. Lactrodectus hesperus has poor eyesight, and they distinguish danger in their habitat by their silk vibration. Only female Lactrodectus hesperus have large enough venom glands for a bite to be harmful and require medical treatment.
The ultimate strength and other physical properties of L. hesperus silk were found to be similar to the properties of silk from orb-weaving spiders that had been tested in other studies. The ultimate strength for the three kinds of silk measured in the study was about 1000 MPa. The ultimate strength reported in a previous study for Nephila edulis was 1290 MPa ± 160 MPa
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