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Western Black Widow

Latrodectus hesperus

Description:

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 millimeters (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 webs. The female's consumption of the male after courtship, a cannibalistic and suicidal behaviour observed in Latrodectus hasseltii (Australia's redback),[2] is rare in this species. Male Western widows may breed several times during their relatively short lifespans.[3] The ultimate strength and other physical properties of Latrodectus 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 Blackledge study was about 1000 MPa. The ultimate strength reported in a previous study for Nephila edulis was 1290 MPa ± 160 MPa[4] Eggs are incorporated into grayish, silken balls about 12 to 15 mm in diameter. These egg masses contain 200 to 900 eggs and are found in the spider's web.

Notes:

The female black widow spider hangs upside down in her web; her red hourglass marking is a visible warning signal. This spider will drop out of its web at the slightest disturbance and pretend that it is dead. The last picture shows its egg sac.


No species ID suggestions

8 Comments

Hema Shah
Hema Shah a year ago

CarolSnowMilne,
http://news.yahoo.com/black-widow-spider...
Black Widow Spiders May Have Met Their Match
Black widow spiders seem to be universally feared. But who's scared of a brown widow? The black widow should be quaking all eight of its boots, a new study suggests. In the United States, there's a new widow in town. The brown widow. And scientists say it may be taking over some native western black widow territory.

CarolSnowMilne
CarolSnowMilne a year ago

WOW!

Hema Shah
Hema Shah a year ago

This black widow looks gravid and might be carrying another egg sac.

Courageous woman you are Emma,here most part of people(expecely women:) have afraid of any spider,with one of those they would freak out :)

Hema Shah
Hema Shah a year ago

Thanks Antonio ,those are the correct words. Not so big and yet so dangerous.
She never goes out of her way to bite any one and she usually stays in her corner. It is only if you mess with her web that she bites.

wow Emma,be careful with that,not big and so dangerous,amazing spotting,very good work,thanks for sharing
we dont have almost any poison animal's in Portugal only viper's,but they are cute amimal's compared to what i se here from almost all the world :)

Hema Shah
Hema Shah a year ago

The female black widow possesses a venom 15 times more potent than rattlesnake venom. The bite is like a pin prick but causes pain within a few minutes of the attack. The pain spreads rapidly to arms, legs, chest, back, and abdomen. Chills, vomiting, difficult respiration, profuse perspiration, delirium, partial paralysis, violent abdominal cramps and spasms may occur within a few hours of the bite. The victim usually recovers in 2 to 5 days; about 5% of all black widow attacks are fatal. The black widow, however, usually bites people only when its web is disturbed. Male black widows do not bite

Hema Shah
Hema Shah a year ago

The last picture shows an egg sac. This egg sac will release about 100 spiderlings.

Tulare, California, USA

Lat: 36.70, Long: -118.76

Spotted on Jun 17, 2012
Submitted on Jun 17, 2012

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