Latrodectus – Black Widow Spider

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 underneath 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.

A bite of any Latrodectus spider contains a dangerous venom and is very painful. Only in very few occasion, however, is its bite lethal.

Adult_Female_Black_Widow
The underside of a female Southern Black Widow showing the red hourglass pattern. Photo: Wikipedia

Description of the Black Widow

The different species of black widows in the US come with different looks. Its iconic trademark, the red hourglass shape on the bottom of its abdomen can be found on the females of all five species of black widows in the US.

In the Northern Black Widow (Latrodectus variolus), the female, male, and immature spider can all look different. When the Northern Widow is young, the abdomen will have red markings down the back, as well as white and yellow stripes on the sides.

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

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.

The Brown Widow (Latrodectus geometricus) has a dark-brown body with a red hourglass shape on its bottom. Its legs are light brown with several black rings around it.

Brown_widow_spider_Latrodectus_geometricus_underside
A brown widow. Photo: Wikipedia

The Red Widow spider (Latrodectus bishopi) has a dark abdomen with red markings on it and orange colored legs. The endangered species lives primarily in sand dunes in central Florida and hardly every comes into contact with humans.

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.

Black Widow Bite

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, less than 1% 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.

The venom of brown widows is less strong than that of the Southern Black Widow. While you should still consult a professional after a bite, it does usually not have any severe effects.

Due to the limited distribution, there have so far no bits of the red widow been recorded. So a bite of a red widow is not something you should worry about.

Range of the Black Widow in the United States

There are several different species of the Widow spiders found in the United States of America. The most commonly found are the Brown Widow, the Northern Black Widow, the Southern Black Widow, the Western Black Widow and the Red Widow.

In the maps below, the shaded areas of the map are where which black widow species is considered to be indigenous. The closer to the edge to a shaded area you get, the less likely it is you will find this spider. Outside of the shaded area it is very unlikely you will find one if you are looking for one.

It is always possible to find any kind of spider in any location, as there is always a chance for the rogue spider. A spider that was moved in luggage, boxes, in a vehicle, etc.

Range of the Southern Black Widow

Southern Black Widow Geographic Distribution Map
The range of the Southern Black Widow in the United States.

The Southern Black Widow can be found throughout the Southeastern states of the US. These are the following: Texas, Oklahoma, Louisiana, Arkansas, Missouri, Illinois, Mississippi, Tennessee, Kentucky, Ohio, Alabama, Florida, Georgia, South Carolina, North Carolina, Virginia, Maryland, Delaware, New Jersey.

Range of the Northern Black Widow

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.

Range of the Western Black Widow

Western Black Widow Range USA Map
The range of the Western Black Widow in the United States

The Western Black Widow (Latrodectus hesperus) can be found throughout the Southern and Western states of the US. These are the following states: Washington, Oregon, California, Nevada, Utah, Arizona, New Mexico, Colorado, Nebraska, Kansas, Oklahoma, Texas.

Range of the Brown Widow

Brown Widow Range Map
The range of the Brown Widow in the United States.

The Brown Widow likes warm temperatures and can only be found in the Southern states of the USA. These are: Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, South Carolina, Tennessee and Texas.

Range of the Red Widow

Red Widow Range Map
Range of the Red Widow in the United States.

The Red Widow (Latrodectus bishopi) is an endangered species and can only be found in Florida.

Scientific Classification of Latrodectus

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

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