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Western Black Widow (Latrodectus hesperus)

The Western Black Widow is a species of venomous spider, indigenous to the western parts of North America. They were previously said to be a part of the subspecies Latrodectus mactans, also a close cousin of the northern black widow (Latrodectus variolus).

Scientific Classification

Western Black Widow

Physical Description and Identification

Adults

Size: Females are 5 inches (127 mm) in length with a leg span between 1.5 and 2 inches (38.1 to 50.8 mm). Males are however smaller about 1/3rd size of its female counterpart.

Color: They have a glossy black body(mostly the females)with red hourglass marking on the undersides of its abdomen, which can also be yellow or even white (which is rare though). The male spiders are not completely black, but have shades of gray or light brown on their body. The hour glass pattern is present in the males too, though it is more of orange than red and at times even yellow.

Other characteristics: The bottom half of the hourglass pattern is slimmer, while the top part is wide.

Western Black Widow Spider Size

Eggs

The eggs attached to the mother’s web are pear-shaped with their color being whitish-yellow or pear-shaped. In a particular sac, there are about 200 eggs which hatch in two weeks from being laid.

Western Black Widow Egg Sac

Spiderlings

Both the males and females have the same color, with the topside being gray or olive, striped in yellow or white. In the undersides of the spiderling’s abdomen, an hourglass pattern or two triangles facing opposite to each other may be seen.

The Web

The web resembles a cobweb made of strong, white silk, found under logs, rocks, big crevices or cracks.

Western Black Widow Web

Is the Western black widow spider poisonous and does it bite

Though members of the Latrodectus genus are known to be harmful, the Western widow spider (especially the males) are not poisonous and does not show aggression, having fewer chances of biting unless provoked or agitated. Their bite might result in a sharp pain just like the pricking of a pin, while some can experience mild symptoms like swelling or redness.

Male Western Black Widow

Quick Facts

Other names Western widow
Lifespan 1 to 2 years
Distribution Western belt of North America, southern Great plains, Mexico and southwestern Canada (British Colombia to Manitoba)
Habitat When outdoors they are known to be terrestrial; if living indoors, they are said to thrive in dwellings of human which are dark, dingy and not frequently accessed
Common predators Birds, wasps, flies as well as other spider species
Diet Mostly insects which get trapped in their web
Western Black Widow Spider

Did You Know

  • When the male succeeds in finding a female for mating he often drums the web of his partner using his abdomen to seek her approval.
  • The species of widow spiders are reputed for killing their mates, but the Western black widow is an exception in this regard.
  • Research conducted at the San Diego State University and Northwestern University has shown that silk produced by them are so strong that they may be used in making textiles for athletes and military.
Western Widow

Image Credits: Acvcsd.org, Nathistoc.bio.uci.edu, Bugguide.net, Images.emedicinehealth.com, M.espacepourlavie.ca, Images.complex.com

The Western Black Widow is a species of venomous spider, indigenous to the western parts of North America. They were previously said to be a part of the subspecies Latrodectus mactans, also a close cousin of the northern black widow (Latrodectus variolus).

Western Black Widow

Physical Description and Identification

Adults

Size: Females are 5 inches (127 mm) in length with a leg span between 1.5 and 2 inches (38.1 to 50.8 mm). Males are however smaller about 1/3rd size of its female counterpart.

Color: They have a glossy black body(mostly the females)with red hourglass marking on the undersides of its abdomen, which can also be yellow or even white (which is rare though). The male spiders are not completely black, but have shades of gray or light brown on their body. The hour glass pattern is present in the males too, though it is more of orange than red and at times even yellow.

Other characteristics: The bottom half of the hourglass pattern is slimmer, while the top part is wide.

Western Black Widow Spider Size

Eggs

The eggs attached to the mother’s web are pear-shaped with their color being whitish-yellow or pear-shaped. In a particular sac, there are about 200 eggs which hatch in two weeks from being laid.

Western Black Widow Egg Sac

Spiderlings

Both the males and females have the same color, with the topside being gray or olive, striped in yellow or white. In the undersides of the spiderling’s abdomen, an hourglass pattern or two triangles facing opposite to each other may be seen.

The Web

The web resembles a cobweb made of strong, white silk, found under logs, rocks, big crevices or cracks.

Western Black Widow Web

Is the Western black widow spider poisonous and does it bite

Though members of the Latrodectus genus are known to be harmful, the Western widow spider (especially the males) are not poisonous and does not show aggression, having fewer chances of biting unless provoked or agitated. Their bite might result in a sharp pain just like the pricking of a pin, while some can experience mild symptoms like swelling or redness.

Male Western Black Widow

Quick Facts

Other names Western widow
Lifespan 1 to 2 years
Distribution Western belt of North America, southern Great plains, Mexico and southwestern Canada (British Colombia to Manitoba)
Habitat When outdoors they are known to be terrestrial; if living indoors, they are said to thrive in dwellings of human which are dark, dingy and not frequently accessed
Common predators Birds, wasps, flies as well as other spider species
Diet Mostly insects which get trapped in their web
Western Black Widow Spider

Did You Know

  • When the male succeeds in finding a female for mating he often drums the web of his partner using his abdomen to seek her approval.
  • The species of widow spiders are reputed for killing their mates, but the Western black widow is an exception in this regard.
  • Research conducted at the San Diego State University and Northwestern University has shown that silk produced by them are so strong that they may be used in making textiles for athletes and military.
Western Widow

Image Credits: Acvcsd.org, Nathistoc.bio.uci.edu, Bugguide.net, Images.emedicinehealth.com, M.espacepourlavie.ca, Images.complex.com

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