Everything You Need to Know About the Bolas Spider

The fascinating Bolas Spider is known for its unique hunting techniques that distinguish it from other spiders.

These creatures employ a special method of capturing their prey, involving a long line of silk with a sticky glob of glue at the end.

Bolas Spiders are nocturnal hunters that primarily target moths. They create their bola by releasing a single strand of silk from their spinnerets and adding a large, sticky droplet at the end.

Source: Judy Gallagher, CC BY 2.0, via Wikimedia Commons

When a moth comes close, the spider swings its bola, snagging the insect midair with impressive accuracy.

This technique is reminiscent of the ancient weapon called a bolas, hence the spider’s name.

These spiders are found in various habitats, including forests, meadows, and even urban areas. They display some interesting features such as strong silk production and excellent vision to detect their prey.

Moreover, due to their specialized hunting strategy, they are capable of capturing larger prey compared to similar-sized spiders.

Bolas Spiders truly showcase the incredible adaptability and diversity present in the arachnid world.

Bolas Spider Overview

Classification and Appearance

Bolas spiders belong to the family Araneidae and the genus Mastophora. As part of the order Araneae and class Arachnida, they are classified as arachnids.

Their unique appearance sets them apart from other spiders. Here are some of the key characteristics of these spiders:

• Body covered in patterns and markings
• Distinct abdomen shape
• Long legs for hunting and spinning silk

Range and Habitat

Bolas spiders can be found in various continents:

• North America
• South America
• Asia
• Africa
• Australia

These arachnids inhabit diverse habitats, ranging from forests to grasslands.

They prefer areas with:

• Plenty of vegetation for web-building
• Abundant insect prey, such as moths

Source: Judy Gallagher, CC BY 2.0, via Wikimedia Commons

Predatory Behavior and Feeding

Hunting Technique

Bolas spiders, belonging to the Mastophora genus, have a unique hunting technique.

Instead of spinning a web, they create a single silk line with a sticky silk ball or “bolas” at the end.

This method resembles a fishing line. Using this bolas, they capture their prey by swinging it effectively.

It is especially effective at catching moths because bolas spiders can mimic the scent of female moths, luring male moths to their doom.

Adult female bolas spiders are known to be more skilled in this technique compared to males and juveniles.

Pheromones and Deception

Bolas spiders employ aggressive chemical mimicry through the use of pheromones to attract their prey, primarily moths.

They release pheromones that mimic the scent of a female moth, luring male moths to approach them.

The ability to produce pheromones varies between bolas spider species.

Pheromone production is typically limited to adult female bolas spiders, which makes them more successful predators than male and juvenile spiders.

Moths as Prey

Moths are the primary prey for bolas spiders. Moth flies and other night-flying insects are attracted to the spider’s pheromones and get caught in the sticky bolas.

Moth species targeted by bolas spiders include M. cornigera and M. Hutchinsoni.

Source: Judy Gallagher, CC BY 2.0, via Wikimedia Commons

Predators of Bolas Spiders

Bolas Spiders, despite their unique hunting techniques and deceptive abilities, are not exempt from the circle of life. Like many other spiders, they face threats from a variety of predators. Here’s a look at some of the primary predators of Bolas Spiders:

1. Birds: Many bird species feed on spiders, and Bolas Spiders are no exception. Birds such as warblers, thrushes, and sparrows might snatch up a Bolas Spider if they spot one.
2. Larger Spiders: The arachnid world is competitive, and larger spider species might prey on Bolas Spiders. For instance, wolf spiders and some orb-weaver spiders, which are known to be aggressive hunters, might see a Bolas Spider as a potential meal.
3. Wasps: Some wasp species are known to target spiders to provide food for their developing larvae. The spider wasp, in particular, is known to paralyze spiders and lay their eggs on them. Once the wasp larva hatches, it feeds on the paralyzed spider.
4. Mammals: Small mammals, such as shrews and certain species of bats, might consume Bolas Spiders if they come across them during their nocturnal activities.
5. Amphibians: Frogs and toads, with their sticky tongues, can quickly snatch up spiders, including the Bolas Spider, as a quick meal.
6. Ants: While not a primary threat, large groups of ants can overpower and consume spiders, especially if the spider is injured or trapped.

Mating and Reproduction

Bolas spiders employ an interesting strategy for attracting prey, particularly moths.

The female Bolas spider releases a chemical that mimics the sex pheromone of female moths.

Males of moth species, such as the small and bristly cutworm, are lured in by this deceitful scent.

The female Bolas spider then captures the unsuspecting male moth with a uniquely shaped web that it weaves between its front legs.

Life Cycle Stages

Egg Sacs

Bolas Spiders have distinct reproductive behaviors, including the creation of specialized egg sacs.

These egg sacs play a crucial role in the lifecycle of the Bolas Spider, ensuring the protection and development of the next generation. Here’s a closer look at the egg sacs of Bolas Spiders:

Structure and Appearance:

Bolas Spider egg sacs are typically rounded or slightly oval in shape.

They are often constructed with a tough outer layer, which provides protection against potential threats and environmental factors.

The exterior of the sac may have a textured or patterned appearance, helping it blend into its surroundings.

Location:

Female Bolas Spiders strategically place their egg sacs in sheltered and concealed locations. This could be under leaves, within crevices, or other hidden spots that offer protection from predators and harsh weather conditions.

Egg Development:

Inside the egg sac, the spider eggs remain protected and nourished. The sac provides a stable environment for the developing spiderlings.

Depending on environmental conditions, the eggs will develop over a specific period before the spiderlings emerge.

Protection:

The tough exterior of the egg sac acts as a barrier against many potential threats. It’s resistant to desiccation (drying out) and can deter some predators.

Some Bolas Spiders may stay close to their egg sacs, guarding them against potential threats. However, this behavior can vary among species.

Number of Eggs:

The number of eggs within a Bolas Spider egg sac can vary based on the species and the health and age of the female. Typically, an egg sac can contain several to many eggs.

Spiderling (Juvenile) Stage:

Emergence: Once developed, the spiderlings emerge from the eggs. At this stage, they are miniature versions of the adults but lack full coloration and patterns.

Molting: Spiderlings undergo several molting processes as they grow. Molting involves shedding their exoskeleton, allowing them to increase in size. This stage is crucial as the spiderlings are vulnerable to predators during each molt.

Subadult Stage

Growth: As the spiders continue to grow, they approach their adult size and begin to show more defined characteristics of their species.

Hunting: Even in this stage, the spiders start practicing their unique bola hunting technique, albeit with less proficiency than mature adults.

Adult Stage

Maturity: Once they reach the adult stage, Bolas Spiders are fully grown and have all the distinctive features of their species, from coloration to patterns.

Reproduction: Mature females release pheromones to attract males for mating. After successful mating, the females lay eggs, ensuring the continuation of the next generation.

Hunting Mastery: Adult Bolas Spiders are experts at using their bola technique. They produce a silk thread with a sticky end, mimicking the scent of female moths to attract male moths, and then swing their bola to capture the lured prey.

Source: Judy Gallagher, CC BY 2.0, via Wikimedia Commons

Lifespan

Bolas Spiders, like many other spider species, have a limited lifespan.

While the exact duration can vary based on environmental factors and predation, they typically live long enough to reproduce and ensure the survival of their species.

Bolas Spider Species

Mastophora Cornigera

Mastophora Cornigera is a species of bolas spider that uses its exceptional silk spinning and chemical abilities while hunting. Their appearance includes:

• Color: Brown females, white males
• Size: Adult females larger than males

These spiders emit chemicals resembling moth pheromones to attract prey, and they use a unique glue-ended silk thread (real bolas) to ensnare them ¹.

Mastophora Hutchinsoni

Mastophora Hutchinsoni is another bolas spider species. It can be found in Minnesota and shows similarities to the Cornigera species. Key characteristics:

• Activity: Primarily nocturnal
• Feeding: Specialized techniques like Cornigera

Mastophora Hutchinsoni also displays targeting techniques using pheromones and unique silk threads for hunting.

Magnificent Spiders: Ordgarius magnificus, O. furcatus, and O. monstrous

Ordgarius Magnificus:

• Appearance: Ordgarius magnificus is known for its striking appearance, often characterized by a vibrant coloration that blends shades of brown, black, and sometimes reddish hues. The abdomen is typically adorned with patterns that aid in camouflage.
• Habitat: This species is primarily found in parts of Australia, especially in regions with dense vegetation.
• Behavior: Like other Bolas Spiders, O. magnificus employs the bola hunting technique, using a sticky silk thread to capture moths. Their nocturnal nature ensures they remain hidden from potential predators during the day.

Ordgarius Magnificus.

Source: File. (2011, September 11). In Wikipedia. https://en.wikipedia.org/wiki/File:Ordgarius_magnificus7.jpg

O. Furcatus:

• Appearance: O. furcatus has a slightly more elongated abdomen compared to O. magnificus. Its coloration is a mix of browns and blacks, with distinctive markings that provide effective camouflage against bark and leaves.
• Habitat: This species is also native to Australia and prefers habitats that offer ample vegetation and a steady supply of moth prey.
• Behavior: O. furcatus is adept at using its bola to capture prey. Additionally, it’s known to release pheromones mimicking those of female moths to attract male moths, which then become easy prey.

O. Monstrosus:

• Appearance: As the name suggests, O. monstrosus is one of the larger species of Bolas Spiders. It boasts a robust and slightly hairy body, with a coloration that ranges from dark browns to blacks, often with intricate patterns on its abdomen.
• Habitat: Found in specific regions of Australia, this spider prefers wooded areas where it can easily blend into its surroundings and remain undetected.
• Behavior: O. monstrosus is a master of deception. Not only does it use the bola technique to hunt, but it also employs aggressive mimicry, releasing pheromones to lure unsuspecting moths. Its larger size allows it to tackle slightly bigger prey compared to its counterparts.

Other Notable Species

Dizzydeani

Dizzydeani is a South African bolas spider species known for its distinct appearance featuring:

• Color: White abdomen, brown and white legs

Cladomelea

Cladomelea is a species of bolas spider that is larger than most of its counterparts in the Mastophora genus.

Bisaccata

Bisaccata is a bolas spider species that has a preference for high altitudes and tree trunks.

Source: Judy Gallagher, CC BY 2.0, via Wikimedia Commons

Archeri

Archeri is another species of bolas spider that showcases similarities in appearance and hunting techniques to other species in the Mastophora genus.

Conclusion

The Bolas Spider, a marvel of the arachnid world, showcases nature’s ingenuity with its unique hunting technique.

Using a combination of pheromones and a sticky bola, it deceives and captures moths, its primary prey.

Found in diverse habitats across continents, this spider stands as a testament to evolution’s creativity.

Its various species, each with distinct traits, further highlight the adaptability and diversity of this remarkable creature.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about bolas spiders. Scroll down to have a look at some of them.

Letter 1 – Bola Spider

What kind of a bug is this?
i sent this e-mail on Jan 14th asking about this bug. I have not heard anything back yet. I wanted to make sure you recieved the e-mail and pictures. My first grade class is continually watching the spider and trying to figure out what it is but have not found anything yet. Please let me know that you recieved this e-mail and if you know anything about our friend. thanks again. anxiously waiting
Stephanie

(01/14/2006) I am a first grade teacher in Houston, Texas and this past week while on the playground my class found this bug (spider I believe). At first we thought it was dead. It was hanging from a tree all curled up.

One of the kids kicked it and knocked it off (right before getting in trouble). At that point we really expected it to be dead and thought we could take it inside and look at it under a microscope. With the end result being that we find out what kind of a bug it is. After putting it in a plastic container with some woodchips from around the tree, we noticed several sacs hanging from the tree as well.

We used a stick to take one and put it in the bottom of the container. After about 10 minutes inside the container the bug started moving. It has a hard shell as the large part of the body. As you hopefully can see in some of the pics there are bumps on the spiders back. One of the pictures is of the spider upsside down holding a piece of wood.

After putting the spider on the coffee filter to take the pictures it quickly started forming some webbing so that it could get to the top of the container. We put the filter on the top so it could get air but nothing be able to get out (hopefully).

Within minutes of putting the spider back in the container it was on the top. The next day when we got to school, we noticed that the spider had made another egg sac? we think hanging from the top of the container. I had taken the pics the day before and didn’t want to open the container since we didnt know what it was.

So anyways, we are wondering what this is? is is dangerous? How long will the egg sac be there before something happens? How many eggs could be inside it? and any other wonderful information I could share with my first graders. Please let us know as soon as possible and if you can’t see the pics let me know as well.
Stephanie Johnson

Hi Stephanie,
Please forgive us for the delay. As the website is just a pastime, we are unable to answer every letter and yours got lost in the shuffle. This is a Bola Spider, Mastophora bisaccata. Its food of choice are moths.

According to our Audubon Guide: “Hard, globular egg sac has long silken extension and is encircled with a series of irregular points. Sac is place on tree branches. Spiderlings emerge in June. … This spider does not spin a web, but produces a dangling silken line with a globule at the end that resembles the South American bola.

Supposedly the 2 protuberances on the spider attract male moths. The spider waits for the moth to approach, then throws its bola at the moth, usually snaring its wings. The spider drops down on a line spun from its spinnerets and eats the entrapped moth.” By the way, you must be an awesome teacher to take such an interest and to pursue the answers.

Letter 2 – Bola Spider

Bola (bolas) spider
What a wonderful site you have! I do not have an insect I wish to identify, but I do have a spider that I think you will appreciate having on your site. It is a bola (or bolas) spider (please correct me if I am wrong).

I’ve never seen one in my 52 years, and I spent 12 hours over several nights getting the following shots. It was very hard to catch her while her droplet of attractant was hanging. Any disturbance and she would reel it back up for a half hour. Lighting was from two separate 8-LED flashlights mounted on both sides of the camera.

I was also fortunate enough to find her daytime resting spot (she looked just like a bird dropping). To top it off, weeks later she made an egg sack! (I didn’t know what image size you desire, hope these aren’t too poor quality, or too large a download).
Steve Davis
Wadesville, Indiana

Hi Steve,
Your are far too humble. Your photos are wonderful. Your night action photos are quite spectacular. According to Audubon: “This spider does not spin a web, but produces a dangling silken line with a globule at the end that resembles the South American bola.

Supposedly the 2 protuberances on the spider attract male moths. The spider waits for the moth to approach, then throws its bola at the moth, usually snaring its wings. The spider drops down on a line spun from its spinnerets and eats the entrapped moth.”

Bolas spider. (11/21/2006)
Daniel:
That bolas spider story and images are just too cool!!! I have never seen one either. I didn’t know they ranged that far north, actually. I was under the impression they were chiefly tropical arachnids. They are not little tiny things, either!

My understanding is that the spider actually manufactures a secretion that mimics the pheromones of certain moth species, thus attracting the male moths.

Whether this substance is on the spider itself, or applied to the globular ball, I don’t know. Truly fascinating, though. The submitter should get some kind of award for his patience and observation skills!
Eric
P.S. Happy Thanksgiving to you and Lisa.

Letter 3 – Unknown Bolas Spider from Georgia

Bolas Spider
Hi again,
I wanted to share this awesome spider I came across at the Sandy Creek Nature Center in Athens, GA where I volunteer. It appears to be a female Bolas spider, but different from the two species shown on BugGuide. ra

I’ve continued to check up on her for two weeks (most recently October 2nd,) and I’ve never seen her move (though she’s clearly alive, and I read that Bolas are nocturnal.) In the last photo, there is an object to the left of the spider that may be an egg sac.
Carmen Champagne

Hi Carmen,
We agree that there are enough similarities to believe this is related to the Bolas Spiders, but it is possible it is even a differnt genus. Your spider does not possess the abdominla bumps that the Mastophora genus pictured on BugGuide posess.

Have you submitted your images to BugGuide? If you ever get an exact identification, we would love to know about it. Meanwhile, we will check with our own group of experts to try to get assistance.

Confirmation (10/05/2007) From Eric Eaton
Hi, Daniel:
Wow. Good eye even to spot one of those! It is definitely a species of Mastophora, but there are 15 U.S. species in the genus and I don’t know how to segregate them.

I’d have to look up a technical reference. It is possible that Jeff Hollenbeck over at Bugguide might know more, but he hasn’t even visited Bugguide for awhile to my knowledge…. Neat find.
Eric
P.S. Thanks again for the continuing free publicity for the field guide. I wish I could tell you how many people have bought it because of the mention at WTB.

Spider Fan Susan checks with an expert
(10/07/2007)
Dear Daniel,
I tried one person in Kentucky who I think somewhat knows the Bolas spiders:
Susan

Dear Blake Newton,
I hope you don’t mind my sending you this image of a bolas spider from Georgia. … I suppose this bolas is perhaps most likely to be one of these four species: Mastophora archeri, M. bisaccata, M. hutchinsoni or M. phrynosoma? Do you have any idea by any chance? Thanks a million,
Susan

Hi Susan,
I have never seen this one before, but I agree that it looks like a Mastophora of some kind. Maybe it is one that lives in GA but not KY? I was hoping it would be on Bugguide, but it looks like you’ve already checked that resource! Very interesting. I’d like to know if you find anything. Sincerely,
Blake Newton
Extension Entomology
University of Kentucky

Letter 4 – Bolas Spider with Egg Sacs

Subject: Bolas Spider and egg sacs
Location: Jamul, CA (east of San Diego)
December 6, 2015 1:03 pm
Saw these “blueberries” dangling from chainlink this morning. After looking them up on your site, I went back and took a picture of mama. (Incidentally, this is my second bird-poo disguised find of the season. The first was swallowtail larva the size of my pinky!)
Signature: Leslie

Dear Leslie,
Your images are a wonderful documentation of the distinctive eggs sacs and excellent camouflage of the Bolas Spider, Mastophora cornigera.  The Bolas Spider and the Caterpillar of a Giant Swallowtail both benefit from their resemblance to bird droppings.

Letter 5 – Bolas Spider in Mount Washington

Subject:  Bird Poop Mimic Spider
Location:  Mount Washington, Los Angeles, California
March 11, 2014  7:30 PM
We noticed this Spider under the post for the bird feeder, and we were struck by its excellent mimicry of bird droppings, but we could not turn around to take photos prior to leaving for work this morning. 

We remembered the spider as it was getting dark, but we decided to take a few images anyways.  Tomorrow we plan to attempt to reshoot with more light, hopefully getting sharper images with better exposure.

We quickly matched this spiders interesting coloration and distinctive shape to a Bolas Spider, Mastophora cornigera, pictured on BugGuide.  According to BugGuide:  “Glistening appearance, like a fresh bird dropping, and pair of lumps on the dorsal surface of the abdomen seem to be genus-wide traits. 

The female spiders can be narrowed down by whether they have abdominal humps or not. However, this field marking does not work for males which can have humps or no humps in the same species” and “The only species in the west is M. cornigera.” 

BugGuide also notes that they feed on:  “Flying insects; certain species specialize on particular species of moths, to the point of releasing mimics of their pheromones in order to attract prey (virtually all male moths) within capture range.” 

BugGuide also provides this information on the life cycle:  “When egg sacs hatch they release immature females and *mature* males! Presumably an adaptation to avoid inbreeding. Males are short-lived and much smaller (obviously) than females.”  This same behavior applies to a Bird Dropping Spider from a different genus found in Australia, according to the Victoria Museum Website which state: 

“During the day, female Bird-dropping Spiders sit motionless with their legs drawn up against their body; this behaviour combined with their humped abdomen and black and white colouring makes them look just like bird poo.  This is a brilliant evolutionary strategy: no one wants to eat bird poo!

Providing the spider doesn’t move and give away its cover, it will not draw the attention of predators. The male, as is often the case with spider species, is much smaller than the female.  The hunting behaviour of this species is just as remarkable as its appearance: Bird-dropping Spiders releases a smell which resembles the sex pheromone that female moths use to attract males. When male moths fly in to investigate, ready to mate, they are grabbed by a Bird-dropping Spider.”

Letter 6 – Bolas Spider in Mount Washington

Reshoot of the Bolas Spider
Location:  Mount Washington, Los Angeles, California
March 12, 2014 6:45 PM
So, we got home with a bit more light this evening, and we reshot the images of the Bolas Spider that is still hanging out under the post supporting the bird feeder.