Latrodectus Variolus – Northern Black Widow

Latrodectus, the black widow spider is one of the most famed and feared spider genera in the world. Hollywood tends to use only one kind of Black Widow in its films. It is always shown as a shiny black spider with a red hourglass on the dorsal side of its abdomen. However, this is not exactly the only species of the Black Widow that is out there. In the United States, five species of Black Widows can be found: the Southern Black Widow, the Northern Black Widow, the Western Black Widow, the Brown Widow and the Red Widow. While the brown widow and the red widow have a less potent venom, the three species of the black widow in the United States can have seious medical effects for humans. In this article, we are looking specifically at the Northern black widow. Despite its name, this species can be found thoughout the Eastern part of the United States – from Texas to Florida up to Michigan and Maine.

Description of the Northern Black Widow

In the Northern Black Widow, the female, male, and immature spider all look different. A young northern widow, has red markings down the back of the abdomen, as well as white and yellow stripes on the sides. Since the range of the Northern black widow overlaps with the closely related Southern black widow, these two species are often confused. The best way to identify the species of a female is by looking at the hourglass shape. In female northern black widows, the hourglass is usually divided into two triangles while the two parts of the hourglass of the southern black widow (as well as the western black widow) are joined together.

Broken hourglass shape of a Northern black widow latrodectus variolus female
A great view on the broken hourglass shape on a female northern black widow. Photo: Judy Gallagher

As they reach adulthood, the male Northern Widows will keep those markings, but it will stop eating and live with only one purpose: to mate. As it wanders, looking for a mate, the abdomen will shrink. The adult female, will lose the white and yellow markings on the side for the most part. In some cases, they will retain some of the markings, but for the majority, they will only retain the red spots down the back.

Latrodectus variolus northern black widow male
A male northern black widow in bad shape. It is missing several legs and its abdomen is shrunk. This spider is definitely at the end of its lifecycle. Photo: Judy Gallagher

All three species of the black widow in North America are often confused with the Steatoda grossa spider, also called the false black widow.

Size

The body in an adult female black widow is about half an inch (13mm) from front to back. Including the legs, the adult female black widow can be about 1.5 inches (38mm).

Web

The web of the black widow is very erratic and tangled looking. The spider will often hang upside down in the web and wait for an insect to get caught up in the web. In this position, it is possible to see the red hourglass marking on the underside of its abdomen.

Northern black widow latrodectus
The red dots on the abdomen of a Northern Black Widow. Photo: Mark Fogler – Newaygo County, Michigan

Northern Black Widow Bite

As the other spiders from this genus, Northern Black Widows are not aggressive spiders. But on occasion, they will bite. Especially if they are defending themselves or their egg sac.

Even though the Black Widow is the most venomous spider in the United States, only a very small amount of its bites will result in death. Young children and elderly adults are most at risk of fatality if the bite injects its venom.

Only female black widow spiders are strong enough to bite through human skin and inject their venom.

Often, a black widow can bite without actually injecting any venom, leaving its bite harmless. However, if after being bitten, the victim begins feeling muscle cramps or abdominal pain, they should go to a hospital. Hospitals have medicines to counter the venom of the Southern black widows. However, there is currently no antitoxin available for bits of the Northern Black Widow.

Northern black Widow
A northern black widow. Photographed by: Miriam Quillen, Cedar, Michigan

The bite of a Northern Widow might only feel like a pinprick at first. There may be local swelling and at some point intense pain in the limbs, chest and muscles as well as tremors, labored breathing, nausea, profuse perspiration, vomiting, cold and clammy skin and a weak pulse. The victim may become unconscious and convulsions may occur.

Range of the Northern Black Widow in the United States

Northern Black Widow Range
The range of the Northern Black Widow in the United States.

Even though its name suggests that the Northern Black Widow can only be found in the Northern States of the US, this is not true. The range of the Northern Black Widow spans over the same area as the range of the Southern black widow but it also stretches further up north to Michigan, Wisconsin and also Massachusetts.

The Northern Black Widow can be found in the followin states: Texas, Oklahoma, Louisiana, Arkansas, Missouri, Illinois, Mississippi, Tennessee, Kentucky, Ohio, Alabama, Florida, Georgia, South Carolina, North Carolina, Virginia, Maryland, Delaware, New Jersey, Massachusetts, Rhode Island, Michigan, Wisconsin. Sometimes, species are also found in areas of New York Connecticut, New Hampshire and Maine.

Scientific Classification of Latrodectus variolus

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Subphylum: Chelicerata
  • Class: Arachnida
  • Order: Araneae
  • Infraorder: Araneomorphae
  • Family: Theridiidae
  • Genus: Latrodectus
  • Species: Latrodectus variolus
Latrodectus Variolus – Northern Black Widow

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