Of the Phidippus johnsoni, female and male spiders are very similar in appearance but male jumping spiders usually have a mostly red back (hence the name “red-backed” jumping spider).
They are often mistaken for much deadlier spiders due to their colors – but they are pretty harmless to humans – which will be discussed later in this article.
So grab a coffee or tea, put on your reading glasses, and let’s get started learning all about red-backed jumping spiders.
Red-backed Jumping Spider | Phidippus johnsoni
The Phidippus johnsoni – belonging to the genus Phidippus and commonly referred to as red-backed jumping spiders – are one of the larger species of jumping spiders commonly encountered in the west of North America.
Phidippus johnsoni are known by different names, but some of the most common names include:
- Red-backed jumping spider
- Red-back jumping spider
- Red-backed jumper
- Red-back jumper
- Johnson’s jumping spider
Like all spiders, a red-backed jumping spider has two main body parts which include its abdomen and a fused head and thorax.
With no neck to turn, these spiders rely on their eight eyes to be able to see in the front, around the sides, and toward the back of them.
With this 360 view, red-back jumpers are able to quickly detect prey and predators based on movements and are able to determine how far away the distance is between them.
Like all other jumping spiders, red-back jumpers have fangs that deposit venom into their prey after they pounce.
They have eight legs for swift movements and are very capable jumpers (most being able to jump between 4 to 50 times their own body length).
Red-backed jumping spiders get their name from their colors.
Both male and female red-backed jumping spiders are black with a red back, but the males and females are easy to distinguish based on the bright red color on the back.
Males have a red back with red color covering the majority of the back of their abdomens while females have more of a red hourglass shape on their backs with a black stripe in the middle of their abdomens.
Females have more black on their backs than males do, allowing them to be easily identified as male or female by humans.
Red-backed jumping spider females tend to be larger than the males. Not only do the females have larger bodies, but they also tend to have longer legs than the males.
It should be easy to distinguish most males from females based on their size alone.
Red-back jumping spiders have a wide range of sizes depending on their locations and diets, but the adult females are almost always bigger than the adult males on average – which is represented in the table below.
The size listed is in millimeters.
|Phidippus johnsoni||Adult Male||Adult Female|
|Body Width Range||4 to 7 (mm)||7 to 10 (mm)|
|Body Width Average||6 (mm)||9 (mm)|
While Phidippus johnsoni aren’t the largest of the jumping spider species, they are among some of the biggest based on the average size of the females in the species.
Red-backed jumping spiders are active hunters like all other jumping spiders. They rely on their senses and skills to detect, stalk, and pounce on prey.
They don’t build webs for hunting prey and only use their silk as tethers to protect them when jumping or to build a nest in their habitat.
They are curious by nature and smarter than other spiders.
Red-backed jumping spiders actively hunt and eat insects including crickets, flies, grasshoppers, roaches, and moths – along with many other types of insects.
They are carnivores that inject venom into their prey to liquefy their internal organs so they can suck the juices out for an easy meal.
Some jumping spiders will even prey on and eat other spiders while others may sip a little nectar from time to time, but the red-backed jumping spider’s diet mainly consists of insects.
Red-backed jumping spiders are excellent hunters that pounce on their prey like all other jumping spider species. They actively hunt during the day with their excellent eyesight and other senses.
Cannibalism can occur among the red-backed jumping spider species. Females are known to kill males and eat them sometimes.
This can be a huge hazard for males when attempting to mate.
Mating between males and females will often occur in the habitat where one of the spiders rest during the night and in bad weather.
Although they don’t use a web to catch prey, they sometimes build nests and retreats (for molting) using their silk.
After mating, females will build nests to store their egg sacs that can contain anywhere from thirty to hundreds of little jumping spiders ready to enter the world in a few weeks.
Females can have an average of 5 to 6 clutches per year, depending on the species and environment in which they live.
Red-backed jumping spiders are commonly found in western North America.
They are one of the most common and most populated jumping spider species distributed throughout the western United States and can also be found in parts of northern Mexico and southern Canada.
Red-backed jumping spiders are commonly found in plains, around wooded areas, under rocks and foliage – but can also be found on grapevines, fences, and on the walls of exterior buildings.
Since jumping spiders don’t build webs to hang out in open areas to catch prey, they rely on their surroundings for cover and for when they are trying to rest.
They don’t usually stay out in open areas unless they are soaking up some rays from the sun or actively hunting prey.
Red-backed jumping spiders have an average lifespan of between six months and two years. While they don’t live long lives, they tend to make the most of the time they have.
In captivity, you may be able to get some spiders to live to be around three years old – but at the same time, others may die within the first year.
Red-backed jumping spiders’ lifespans depend on many factors, but they tend to live slightly longer in captivity versus living in the wild.
You may get a longer life out of your pet jumping spider in captivity with the proper diet and care.
But you just aren’t going to get a really long life out of these spiders regardless of how well you take care of them as pets.
Red-backed Jumping Spider | Questions
Below are commonly asked questions about red-backed jumping spiders.
Do Red-backed Jumping Spiders Make Good Pets?
Red-backed jumping spiders can make great pets but whether they can make a good pet for you just depends on what you are looking for in a pet.
Here are some of the things to consider before getting a red-backed jumping spider as a pet:
- Jumping spiders don’t have a long life (1-2 years for most)
- They are shy spiders but are not aggressive toward humans
- Jumping spiders are beginner-friendly pets because they don’t require much
- They don’t require a huge space to live in, just a small habitat because they are small
- Jumping spiders require little care in regards to diet and maintenance
- They are affordable as pets and won’t break the bank
- They “might” be able to be handled if they become comfortable enough around you
You must decide if a Phidippus johnsoni could be the right pet for you based on what you are looking for in a pet and what your current living and financial situations dictate.
Do Red-backed Jumping Spiders Bite?
Red-backed jumping spiders will bite like all other jumping spiders if they feel threatened or are in danger.
They are not aggressive toward humans and don’t have a history of biting unless provoked or hurt in some manner.
You shouldn’t feel scared of red-back jumping spiders because they won’t bite you unless you are causing them some type of harm or if they get frightened.
Most bites that occur on humans only occur because people think just because these little spiders seem friendly, they must want to be picked up and held.
Jumping spiders are not tame, especially if you catch one from the wild and it wasn’t raised domestically.
They may bite when trying to be held because they don’t like it, nor are they used to it, and they don’t know whether you are about to put them in danger or not.
Are Red-backed Jumping Spiders Poisonous?
Although there are some instances where people are bitten by spiders like the red-backed jumping spider, there is no need to seek immediate medical attention unless you have some type of allergic reaction.
However, if an infection occurs around the bite, you may have to seek medical attention due to a bacterial infection, but not because of the venom injected into you by the spider.
Any bite or scratch on your body is susceptible to infection, so a spider bite is no different.
As stated, red-back jumping spiders are not poisonous, but they are often confused with a much deadlier spider as seen in the pictures below.
This spider species is known as redback spiders and they should not be confused with red-back jumpers due to how deadly they can be for humans.
Red-backed Jumping Spiders vs Redback Spiders
If you live in places like Australia, Asia, and New Zealand, it is very important that you don’t confuse red-backed jumping spiders with redback spiders.
While red-backed jumping spiders are pretty much harmless to humans, redback spiders can be very dangerous.
The first two pictures in this article are of a female red-backed jumping spider.
However, the pictures directly above are of poisonous redback spiders (also known as Australian black widows) and should not be confused with the harmless red-back jumping spiders.
Redback spiders are very venomous and pose a significant threat to humans, so it is very important to stress that you shouldn’t mix up the two spider species when attempting identification.
Thanks for stopping by and learning all about red-backed jumping spiders.
As you’ve learned, red-back jumping spiders are some of the largest jumping spiders commonly found in the American west.
Phidippus johnsoni are not poisonous to humans but can sometimes get confused with a much deadlier spider known as a redback spider or Australian black widow.
These spiders can make great pets for the right pet owners because they don’t require much in relation to diet and habitat, but they aren’t good pets for everyone.
Just depends on what you are looking for in a pet.
Thanks again for checking out this article on red-back jumping spiders. If you enjoyed this article, we have a bunch more awesome articles for you to read in our “spiders” category.