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Southern Black Widow (Latrodectus mactans)

The southern black widow, commonly known as the black widow, is endemic to North America. They are closely connected to the western black widow and the northern black widow, resembling their cousins in specific ways.

Southern Black Widow

Scientific Classification

Physical Description and Identification

Adult

Size: Females are mostly 0.31 – 0.51 inches (0.8 – 1.30 cm) long including their leg span while males measure around 0.12 – 0.23 inches (0.3 – 0.6 cm).

Southern Black Widow Size

Color: Sexual dimorphism is prominently visible when it comes to coloration.

Full-grown female species have a black body, with an hourglass-shaped red marking on their abdomen’s underside. They may even have a red or orange patch over their spinnerets on the abdominal top. The male spiders are purple or even have the grayish-black color of the juveniles.

Other Characteristic Features: Both the sexes have round legs, while females are characterized by a rounded abdomen.

Southern Black Widow Male
Southern Black Widow Female

Eggs

Female southern black widows create beige-colored egg sacs sizing 0.39-0.49 inches. The sacs release 200-220 eggs, each having a diameter of around 0.03 inches. The incubation period is generally a month after which the spiderlings emerge.

Southern Black Widow Egg Sac

Spiderlings

All spiderlings have a whitish complexion at first which gradually develops into a black shade with every molt. The distinctive hourglass red spot or other marks usually common in adults are also missing in spiderlings.

The juveniles have a gray or white abdomen with orange and yellow spots and white stripes running across.

The Web

Southern black widows create messy three-dimensional webs in the crevices during the day, and hang upside down.

Southern Black Widow Web

Are Southern Black Widow Spiders Venomous

The females are considered more venomous than their male counterparts as they have larger and sharper mouthparts that can get right into the human skin. The female southern black widow’s venom is called alpha-latrotoxin, which causes several neuromotor problems. Though over two hundred bites have been annually recorded, there have been no instances of fatality in a healthy adult.

Southern Black Widow Habitat

Quick Facts

Other Names Shoe-button spider, black widow
Distribution Southeastern province of the United States and southeastern Canada
Habitat Rodent burrows, rock, and woodpiles
Lifespan Females: 3 – 4 years
Males: 3 – 4 months
Breeding Season Spring and summer
Predators Blue mud dauber, spider wasp, centipede, brown widow spiders
Diet Woodlice, mice, millipedes, and centipedes
IUCN Conservation Status Not listed
Southern Black Widow Spider

Did You Know

  • Danish zoologist Johan Christian Fabricius describe dit for the first time in 1775, placing it in the Aranea genus. Later, Charles Athanase Walckenaer placed it in the Latrodectus genus in 1837.

Image Credits: Entnemdept.ifas.ufl.edu, Venombyte.com, Bugguide.net, Static.inaturalist.org, Spiderid.com, Farm9.staticflickr.com, Thoughtco.com, Upload.wikimedia.org, Cisr.ucr.edu

The southern black widow, commonly known as the black widow, is endemic to North America. They are closely connected to the western black widow and the northern black widow, resembling their cousins in specific ways.

Southern Black Widow

Physical Description and Identification

Adult

Size: Females are mostly 0.31 – 0.51 inches (0.8 – 1.30 cm) long including their leg span while males measure around 0.12 – 0.23 inches (0.3 – 0.6 cm).

Southern Black Widow Size

Color: Sexual dimorphism is prominently visible when it comes to coloration.

Full-grown female species have a black body, with an hourglass-shaped red marking on their abdomen’s underside. They may even have a red or orange patch over their spinnerets on the abdominal top. The male spiders are purple or even have the grayish-black color of the juveniles.

Other Characteristic Features: Both the sexes have round legs, while females are characterized by a rounded abdomen.

Southern Black Widow Male
Southern Black Widow Female

Eggs

Female southern black widows create beige-colored egg sacs sizing 0.39-0.49 inches. The sacs release 200-220 eggs, each having a diameter of around 0.03 inches. The incubation period is generally a month after which the spiderlings emerge.

Southern Black Widow Egg Sac

Spiderlings

All spiderlings have a whitish complexion at first which gradually develops into a black shade with every molt. The distinctive hourglass red spot or other marks usually common in adults are also missing in spiderlings.

The juveniles have a gray or white abdomen with orange and yellow spots and white stripes running across.

The Web

Southern black widows create messy three-dimensional webs in the crevices during the day, and hang upside down.

Southern Black Widow Web

Are Southern Black Widow Spiders Venomous

The females are considered more venomous than their male counterparts as they have larger and sharper mouthparts that can get right into the human skin. The female southern black widow’s venom is called alpha-latrotoxin, which causes several neuromotor problems. Though over two hundred bites have been annually recorded, there have been no instances of fatality in a healthy adult.

Southern Black Widow Habitat

Quick Facts

Other Names Shoe-button spider, black widow
Distribution Southeastern province of the United States and southeastern Canada
Habitat Rodent burrows, rock, and woodpiles
Lifespan Females: 3 – 4 years
Males: 3 – 4 months
Breeding Season Spring and summer
Predators Blue mud dauber, spider wasp, centipede, brown widow spiders
Diet Woodlice, mice, millipedes, and centipedes
IUCN Conservation Status Not listed
Southern Black Widow Spider

Did You Know

  • Danish zoologist Johan Christian Fabricius describe dit for the first time in 1775, placing it in the Aranea genus. Later, Charles Athanase Walckenaer placed it in the Latrodectus genus in 1837.

Image Credits: Entnemdept.ifas.ufl.edu, Venombyte.com, Bugguide.net, Static.inaturalist.org, Spiderid.com, Farm9.staticflickr.com, Thoughtco.com, Upload.wikimedia.org, Cisr.ucr.edu

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