For an animal that looms so large in human perception, the black widow spider has a diminutive size. Even with their legs fully spread, the largest specimens barely reach an inch and a half, with males generally somewhat smaller. Aside from a slight size disadvantage, males also have weaker venom than females. While the iconic image is of a sleek black spider with a striking red hourglass on her abdomen, there are many varieties, including brown bodies, yellow or white markings, red spots, or no markings at all. Early mythology generally treats the spider as a creator, but the black widow is forever associated with their sometimes unfortunate breeding habits.
Black Widow Spider
Scientific & Common Names
Kingdom - Animalia
Phylum – Anthropoda
Class - Arachnida
Order - Araneae
Family - Theridiidae
Genus - Latrodectus
Common Names – Black Widow Spider, Red Back Spider, Widow Spider
Widows can be found on all continents with the exception of Antarctica and, although other widow species can be found in North America, black widows are the prevalent species there. Widows can live from 1-3 years, with the larger females having the advantage. The color of the body can vary from deep black to dark or reddish brown, but they always appear hairless, at least to the naked eye.
Black widows are solitary creatures that only mingle together briefly for breeding purposes. Large numbers can often be found in close proximity, but those individuals remain in their own small territories. While the common belief is that females always consume their male mates, that is not the case. The behavior has been noted in laboratory settings for some species, but the frequency in the wild is unknown. After breeding, females form a cocoon with hundreds of eggs that they suspend in their web. When the spiderlings hatch, they immediately leave the nest with no further contact with their mother. The young more closely resemble males in color and body type and their venom is not considered dangerous to humans at that stage.
Like many, but not all, other spider species, the widows create a web in which they wait for prey. Due in part to their poor eyesight, they do not like to wander far from their web since they rely on the vibrations of the webbing to indicate prey animals or potential threats. Widows are not known to be aggressive towards humans and most bites are defensive in nature. Though not often fatal to humans without a severe allergic reaction, the venom, which contains the neurotoxin latrotoxin, of black widows can be very dangerous, with effects that can last for weeks.
True black widows are found in North America, but widows elsewhere are sometimes referred to by that name, including the grey and red widow spiders found in Australia. The first known true spiders appeared in the evolutionary record 300 million years ago. Today, there are over 40,000 described species of spider.
There is no known risk to black widow spider populations and there is no ongoing attempt to eradicate them since they pose little to no real threat to humans.
The Black Widow & Other Venomous Spiders by Jim Bremner and Kris Bonner
Black Widow Spider (Wildlife, Habits, & Habitats) by Nancy J. Nielsen
Spiders of North America (An Identification Guide) by D. Ubick, P. Paquin, P.E. Cushing, and V. Roth
The Black Widow Spider by Karen M. Vail Associate Professor, Carl Jones, Professor, and Harry Williams, Professor Emeritus Entomology and Plant Pathology