Spiders come in a huge variety of colors, shapes and sizes. Most spiders have bodies that are brown, black, gray or a muted tone that helps them blend into their environments for hunting and avoiding predators. However, some spiders exhibit bright colors like reds, oranges, yellows, whites or iridescent blues and greens. The vibrant colors often serve as a warning to potential predators that the spider may be venomous or unpalatable. One type of colorful marking found on some species of spiders is a reddish or orange underside or abdomen. There are a number of spiders found around the world that have this eye-catching vibrant red or orange coloring on their undersides.
Some of the most notorious spiders that have reddish markings on their undersides are in the genus Latrodectus, known as widow spiders. There are 31 recognized species of widow spiders, found on every continent except Antarctica. Some of the most common species include:
– The southern black widow (Latrodectus mactans) – This spider is found throughout North America. The female is black overall, with a distinctive red or orange hourglass marking on the underside of her spherical abdomen. She has a body length around 1.5 inches. Her venom is neurotoxic to vertebrates.
– The western black widow (Latrodectus hesperus) – Very similar in appearance to the southern black widow, this species is found in western North America. It also has an hourglass marking on the underside.
– The brown widow (Latrodectus geometricus) – Found in tropical and subtropical regions around the world, this species has an overall brown or grey coloration with an orange or yellow hourglass marking underneath. It is slightly less venomous than other widow species.
– The red widow (Latrodectus bishopi) – This widow is found in parts of Florida and southern Africa. It has a very bright red hourglass marking on its underside.
– The Australian redback spider (Latrodectus hasselti) – Common in Australia, this widow spider has a prominent wide red stripe on its abdomen. It is closely related to the other widow spiders.
So in summary, all widow spiders have a red, orange or yellow marking on the underside of their spherical abdomens. This bright coloring serves as a warning to predators that they are venomous. The hourglass shape is iconic for the widows.
While the Australian redback is one type of widow spider, there are also some other spiders in Australia and around the world that are called redbacks, referring to their red markings:
– The South American redback spider (Latrodectus variolus) is found in South America and closely resembles the Australian redback.
– The New Zealand katipo (Latrodectus katipo) is native to New Zealand and can have vibrant red markings across its abdomen.
– Several spiders in the genus Scytodes, also known as spitting spiders, have red markings on their abdomens. This includes Scytodes thoracica and Scytodes fusca.
So while “redback spider” often refers to the Australian Latrodectus hasselti, it can also be used as a descriptive term for other spiders with prominent red markings on their backs or abdomens.
Orb Weaver Spiders
Many types of orb weaver spiders have abdominal markings that can range from orange to red, including:
– The barn spider (Araneus cavaticus) often has reddish-orange markings on its underside.
– The marbled orb weaver (Araneus marmoreus) has vivid red, orange and white markings on its large spherical abdomen.
– Various garden spiders in the genus Argiope can have reddish, orange, yellow or silvery patterns on their undersides, such as the black and yellow garden spider (Argiope aurantia).
– Some spiders in the genus Araneus, such as Araneus detrimentosus and Araneus borealis have reddish or orange markings under their abdomens.
The bright colors serve to attract prey to the webs, while also warning birds and other predators to avoid them.
Some jumping spiders have vibrant red markings, including:
– The daring jumping spider (Phidippus audax) is common in North America and has an orange or red stripe on its abdomen.
– The zebra jumper (Salticus scenicus) has black and white striping on its abdomen and legs, with red or orange patches on the top and bottom.
– The jumping spiders in the genus Plexippus often have red or orange coloration, such as the Plexippus paykulli.
Again, the red markings likely serve as a defense to warn predators of toxicity or bad taste. The jumping spiders are not harmful to humans.
Other Spider Species
Some additional spider species that can exhibit red or orange markings on their abdomens include:
– The redlegged hammock spider (Cupidaroa picta) has bright red legs and red stripes on its abdomen. Found in the Americas.
– Some species of lynx spiders in the genus Oxyopes, such as the western lynx spider, have bright reddish or orange stripes and patterns on their abdomens.
– The ladybird spider (Eresus cinnaberinus) is aptly named for its bright red body with black spots, similar in coloring to a ladybird beetle. It is found in parts of Europe and North America.
– Some wolf spiders in the genus Hogna exhibit orange or red markings, such as the Carolina wolf spider (Hogna carolinensis).
So in summary, red or orange abdominal markings are found in a variety of spider families across multiple continents, serving various functions from attracting prey to deterring predators. The iconic widow spiders are some of the most notorious red-bottomed spiders globally.
While most spiders have more neutral body coloration, some unusual species display brighter warning colors like reds, oranges and yellows on parts of their bodies. One area where these vibrant colors often occur is on the spider’s abdomen or underside. Some of the most common spider families that include species with reddish or orange markings on their undersides are:
– Widow spiders like the black, brown, red and Australian redback widows
– Orb weaver spiders like garden spiders and marbled orb weavers
– Jumping spiders such as the daring jumper and zebra jumper
– Other diverse spiders like lynx spiders, hammock spiders, ladybird spiders and wolf spiders
The red or orange undersides serve important functions from attracting insect prey to their webs to signaling toxicity and warning off bird and mammal predators. While the widows are potentially medically significant spiders, the vast majority of red-bottomed spiders are harmless to humans. So a flash of red on a spider’s belly can be appreciated as a colorful warning sign and reminder of nature’s diverse designs.
 Spider Identification. “Spider Color Markings, Why Are Spiders Colored As They Are” https://www.spideridentification.org/spider-color.html
 InsectIdentification.org. “Red and Black Spiders” https://www.insectidentification.org/insect-description.php?identification=Red-and-Black-Spider
 Beccaloni, J. (2009). Arachnids. University of California Press.
 Bradley, R.A. (2012). Common Spiders of North America. University of California Press.
 Wikipedia contributors. “Latrodectus.” Wikipedia, The Free Encyclopedia. https://en.wikipedia.org/wiki/Latrodectus
 Mammola, S. et al. (2017). “Pattern and process in the colour polymorphism of Theridiid spiders.” Scientific Reports. 7: 3641.
|Spider Family||Example Genera||Locations||Marking Description|
|Theridiidae||Latrodectus||Worldwide||Red hourglass shape on abdomen underside|
|Araneidae||Argiope, Araneus||Worldwide||Red or orange stripes, spots or patches on abdomen|
|Salticidae||Phidippus, Plexippus||Worldwide||Red or orange stripes or patches on abdomen top/bottom|
|Oxyopidae||Oxyopes||Americas, Africa||Red or orange stripes/patterns on abdomen|