Why Do Spiders Mimic Ants? Truth Revealed

Spiders have evolved strange and unique ways to live and hunt in the wild. But did you know that some spiders mimic ants for this purpose? Learn all about this amazing trick of nature and why spiders do it.

Insects never fail to amaze us with their novel hunting and survival tactics. 

Myrmecomorphy, or the mimicry of ants, is one of the oldest and most interesting of these survival strategies among arthropods, and spiders aren’t far behind in adapting it. 

If you ever find an odd-looking ant that is away from its other ant friends, take a closer look – you might find it is a spider in an ant’s clothing! 

More than 300 species of spiders use myrmecomorphy for various reasons. Let’s explore the topic and find out more about why and how spiders mimic ants.

Myrmarachne Formicaria

Why Do They Do It?

Considering spiders are already successful predators with venomous bites, large size, agility, and strength, you might be wondering why some of them bother to mimic ants. 

Well, the reason varies from one species to another, but it’s usually either a form of defense or a predatory tactic. Let’s explore some of these reasons with examples.

To Fool Predators

While it’s true that spiders themselves are well-known predators, they are far from being at the top of the food chain. 

A variety of other predators, like wasps and birds, tend to prey on them. However, the same predators have an aversion to ants because they are usually either too aggressive or unpalatable. 

Spiders that mimic ants use this to their advantage. They mimic ants, and these predators think that they are unattractive as food. This, in turn, helps avoid them being made larvae food by wasps.

This type of mimicry, i.e., mimicking ants for defensive purposes, is known as Batesian mimicry

The ant-mimicking jumping spider (Myrmarachne) offers one of the best examples of this tactic. The smaller spiders of this species are often preyed upon by larger jumping spiders and ants. 

They keep themselves safe from these larger predators by looking like ants themselves. 

Spiders aren’t the only Batesian mimics; certain species of thrips, mantises, flies, and even plants use this form of defense against predators.

Ant -Like Crab Spider

To Fool Their Prey

Not all species of ant-mimicking spiders do it solely for defense against predators – some also use this tactic for hunting. 

Known as aggressive mimicry, it’s particularly helpful to spiders that hunt prey that doesn’t usually consider solitary ants a threat but are afraid of spiders. 

Most species of ants are powerful predators when they work as a team, but far less dangerous when they’re alone. 

Thus, spiders pretending to be ants can avoid being detected by their prey if they mimic ants.

By pretending to be an ant, a spider can get close to its unsuspecting prey and launch a swift attack. 

Besides helping the spiders hunt, aggressive mimicry also enables them to carry the prey safely through ant territory. 

A regular spider passing by an ant colony while carrying the corpse of its prey is far more likely to be attacked by the ants.

Staying Near Ants For Protection

This is also a defensive tactic, but it’s a little different from the Batesian mimicry described earlier. 

Some spiders enjoy indirect protection by living near ants rather than appearing as ants to the predator (they can do both also).

This behavior is especially noticeable among spiders trying to keep themselves safe from spitting spiders. 

The spitting spiders are particularly fearsome predators, capable of shooting out a mix of venom and spider silk. 

Long-palped Ant-mimic Sac Spider

They build their webs directly above the nests of salticid spiders (jumping spiders) and use the advantage to hunt and feed on them. 

However, they have an aversion to ants, and the ant-like jumping spider takes advantage of this. 

These spiders often build their nests near those of highly territorial ants, like weaver ants. By being close to their enemies, they avoid becoming food for the spitting spiders.

Of course, living so close to ants that show predatory behavior towards spiders has its fair share of dangers. 

To avoid getting preyed upon by the ants they’ve turned to for protection, jumping spiders build hardy nests with confusing entrances that ants cannot invade.

To Prey On The Ants

Generally speaking, ants are dangerous prey for spiders due to their strong defenses. 

Their ability to use sting with formic acid, deliver painful bites, and attack in large numbers often makes them difficult to prey upon. 

Certain spiders capable of myrmecomorphy get around this challenge by pretending to be ants.

Lone ants, away from the protection of their colony, are the ideal prey for these ant-mimicking spiders. 

This behavior is particularly noticeable among the spider species Aphantochilus rogersi, which prey on Cephalotini ants by mimicking them and living close to their colony.

In What Ways Do Spiders Mimic Ants?

Now comes the most interesting part – finding out how these spiders manage to pull off this impressive feat of mimicking a completely different species. 

Upon closely examining the ant-mimicking spiders, researchers have found them using the following tactics:

The number of legs

Spiders have four pairs of legs, whereas ants have three. This is a clear difference visible to anyone, so ant mimic spiders need to fix it somehow. 

They remedy this by raising the front pair of legs to make them look like antennae. 

Although they use all eight legs to walk, they make frequent stops in the six-legged stance. This makes it almost impossible to notice that they’re walking on four pairs of legs.

Appearance

Some of these spiders also share visual similarities with ants. Besides having a similar color, they also have fake thread waists. 

They do this by having a long tube-like connecting part between the thorax and abdomen.

These waists make their bodies appear to have three segments, although they have only two.

Orange Ant-mimic Sac Spider

Chemical mimicry

The formic acid carried by ants gives them a distinct smell that other ants or predators can recognize. 

Some spiders mimic even this smell by rubbing formic acid from dead ants over themselves.

Behavioral mimicry

Spiders that mimic ants can even replicate various ant-like behaviors. For example, they run around constantly with very short pauses, just like ants. 

They even follow a roundabout path when moving. This behavior is specific to ants following pheromone trails left by other ants.

The resourcefulness of ant-mimicking spiders is certainly remarkable and goes on to show how amazing spiders can be.

Frequently Asked Questions

Do spiders like ants?

Unlike many other common insectivore predators, spiders like ants as food. Many species of spiders specifically mimic ants to get close to ants and hunt them. 
You may often notice household spiders feeding on ants, too, besides other insects like moths, fleas, and mosquitos.

Why do insects mimic ants?

Myrmecomorphy, or the mimicry of ants, is a common behavior found among a variety of insects and other arthropods. 
Most of them do this to protect themselves from predators that usually refrain from eating ants. Some also mimic ants as a hunting tactic – a behavior known as aggressive mimicry.

Do Ant mimicking spiders eat ants?

Yes, while some species of spiders pretend to be ants, it doesn’t necessarily mean they’re friendly toward their model ants. 
Certain types of ant-mimicking spiders even carry out this mimicking behavior specifically to turn ants into unsuspecting prey and eat them.

Are Ant mimic spiders poisonous?

The venomousness of ant mimic spiders varies from one species to another. With more than 300 types of spiders that mimic ants, it’s only normal that some are more poisonous than the rest. 
However, even among the poisonous ones, most aren’t that dangerous to humans besides the risk of triggering allergies.

Wrap Up

Impressive how spiders can mimic a species with very different behavior and appearance, isn’t it? 

Both their predatory behavior and defensive strategies are intriguing, to say the least. I hope you enjoyed exploring this topic as much as we did.

Thank you for reading!

Reader Emails

Many of our readers have sent us in lovely pics of these creatures, asking us to tell them why these creatures look so much like ants. Please go through some of these emails below.

Letter 1 – Red Spotted Ant Mimic Spider

 

Spider in Utah July 29, 2009 I came across this spider while walking in a desert scrub area near a creek. It was about the size of a quarter or maybe a little smaller if I remember correctly. Any idea what it might be? Curious about Critters Cedar City, Utah
Red Spotted Ant Mimic
Red Spotted Ant Mimic
Hi Curious, Using BugGuide, we believe we have identified your spider as a Red Spotted Ant Mimic, Castianeira descripta.  According to BugGuide:  “Although like most spiders this species is equipped with vemon to subdue its prey, it is not considered harmful to humans.”

Letter 2 – Ant Mimic Spider

 

Orange Tiger Striped Spider June 23, 2010 This was the coolest looking spider I could hardly see. He was barely 1/4 of an inch long, and looked as though he was ready to pounce upon me. I looked at him, He looked back, so I got my camera, and found him once again on my porch. He rared his abdomen up at an angle, then he started “twirling” it around right before he jumped.. He could jump about 8 inches in one leap, and was very very fast when he ran. I did not notice his tiger stripes until I looked at the photographs. I tried to get a nice macro shot, but he just didn’t want to wait till I adjusted my shutter speed… Each time I would go in for a shot, he would wiggle his butt, then jump off to the left or right. He tried to go under an object, I carefully moves it off from him, and so the showdown began. Date of the picture is 6/23/10 Rick Nelson (SCWIDVICIOUS) Lexington, NC
Antmimic Spider
Hi Rick, Using BugGuide, we quickly identified your spider as Castianeira amoena, a species in the family Corinnidae, commonly called Antmimic Spiders or Ground Sac Spiders.

Letter 3 – Ant Mimic Ground Sac Spider

 

Subject: Pretty spider Location: Stillwater OK July 22, 2017 6:07 am Found this spider in my dining room this morning. I’ve never seen one like this before. Signature: Angela
Ant Mimic Ground Sac Spider
Dear Angela, This is one of the Ant Mimic Ground Sac Spiders in the family Corinnidae, and we are confident we have identified is as a species with no common name, Castianeira amoena, thanks to images on BugGuide.  According to SpiderBytes:  “Some Castianeira species are thought to mimic velvet ants (Mutillidae), rather than ants. Mutillids are not actually ants but wasps, and the females are wingless and brightly coloured, with extremely painful stings. In this case, harmless Castianeira spiders might benefit by looking like the much more dangerous velvet ants, and thus be avoided by predators (this is called Batesian mimicry).”

Letter 4 – Ant Mimic Spider, but which species???

 

Subject:  Spider Geographic location of the bug:  Los Angeles, California, USA Date: 05/04/2019 Time: 02:21 AM EDT Your letter to the bugman:  I found this spider on the wall of our house- outside. It’s May 4th (May the 4th be with you.) How you want your letter signed:  Allison
Ant Mimic Spider
Dear Allison, This is a harmless Ant Mimic Spider in the genus Castianeira, and it is most likely Castianeira occidens, which is native to Southern California and which is pictured on both BugGuide and the Natural History of Orange County.  We do have our doubts as its markings more closely resemble Castianeira crocata , which is pictured on BugGuide, and also the Red Spotted Ant Mimic Spider, Castianeira descripta, which is also pictured on BugGuide, but both of those are eastern species.  It is not entirely impossible that one of the eastern species might have been introduced to Southern California.  The species identification confusion is also noted on BugGuide where it states:  “The following ID tips come from Reiskind, 1969. Corresponding page numbers are listed below. …  The next group is C. crocata (pg. 200), C. descripta (pg.208), C. occidens (pg.211) & C. floridana (pg.201). C. occidens can be separated from the other two by the white stripe on the carapace. At this point we aren’t sure we can separate C. crocata & C. descripta. It’s possible that the red mark goes all the way to the rear in C. descripta and stops short in C. crocata. Also, males of C. descripta have ‘some white hairs at the posterior end’. C. floridana is easier to separate because it’s only found in peninsular Florida, but range may overlap with C. descripta.”

3 thoughts on “Why Do Spiders Mimic Ants? Truth Revealed”

  1. Most all spiders bite, but are usually not dangerous. They can be painful. A small jumping spider bit me long ago, but I still remember that it felt like a wasp sting.
    You likely know the very dangerous widows of which there are several, and the brown recluse or violin spider.

    Reply

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