Spined Micrathena: Essential Guide for the Curious Observer

Spined Micrathena spiders are fascinating creatures that you might have encountered while walking through wooded areas. These orb-weaving spiders belong to the genus Micrathena and are known for their unique appearance, featuring a chunky, spiny abdomen. In Missouri, there are three species of spiny orb-weavers, with the spined Micrathena being one of the most common.

As you delve into the world of Spined Micrathenas, you’ll discover their intriguing colors, which range from white to yellow and are mottled with black or brown. Female spined Micrathenas are particularly captivating, as their ten-spined, chunky abdomen sets them apart from all other spiders. Males, on the other hand, are much smaller and don’t spin webs like their female counterparts.

In this article, you’ll learn all you need to know about Spined Micrathenas, including their habitat, behavior, and the role they play in the ecosystem. By the end, you’ll have a newfound appreciation for these remarkable arachnids!

Basic Description of Spined Micrathena

The Spined Micrathena is a type of orbweaver spider that can be easily identified by its unique appearance. You’ll notice that these spiders have distinctive patterns on their bodies, which are often black and white, with mottled yellowish areas. The most striking feature of the Spined Micrathena is its spines or conical tubercles running along the lateral margins of its abdomen. These spines provide the spider with a castleback appearance.

In terms of size, they’re generally quite small, although females are usually bigger than the males. Moreover, the female spiders possess a more robust, chunky abdomen compared to their male counterparts. This size difference makes it easier to identify between the two sexes. The elongated spines are more prominent in females, giving them a distinctive look compared to other orbweavers like the castleback orbweaver.

To recap the features of Spined Micrathena:

  • Black and white, mottled yellowish body
  • Prominent spines or conical tubercles on the abdomen
  • Chunky abdomen in females

When observing Spined Micrathena spiders in nature, you’ll likely come across them in woodland areas, as they prefer this type of environment for spinning their intricate webs. In essence, they’re a fascinating example of the diverse world of orbweaver spiders, with their unique appearance and color patterns genuinely setting them apart from the rest.

Remember, spiders like the Spined Micrathena may seem intimidating, but they’re essential to the ecosystem, playing a crucial role in controlling insect populations. So next time you stumble upon one, instead of shying away, take a moment to appreciate these captivating creatures.

Scientific Classification

The Spined Micrathena belongs to the family of spiders known as Araneidae and falls under the order Araneae. They are part of the Genus Micrathena, which includes several unique orb-weaving spiders. Here is a quick overview of their classification:

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Subphylum: Chelicerata
  • Class: Arachnida
  • Order: Araneae
  • Suborder: Araneomorphae
  • Family: Araneidae
  • Genus: Micrathena

These spiders are fascinating creatures mainly characterized by their striking appearance and the complex webs they weave. Let’s dive into some of their features.

Female Spined Micrathena spiders are easy to identify due to their distinctive abdomen shape and a series of spines or cones around their bodies. For example, the Spined Micrathena (Micrathena gracilis) has five pairs of black tubercles encircling its abdomen, which can be mottled with black or brown, white, or yellowish colors. On the other hand, the White Micrathena (Micrathena mitrata) has two short pairs of tubercles and a white abdomen with a few distinct black blotches.

When comparing these spiders with others in the Araneidae family, you will notice that their scientific classification shares similarities such as being part of the same order (Araneae) and family (Araneidae). However, they differ at the genus level, with Micrathena spiders having unique characteristics.

In summary, understanding the scientific classification of the Spined Micrathena and related species helps you appreciate their position within the spider world. This knowledge will also aid in identifying these creatures and learning more about their fascinating biology and behaviors. While exploring, keep your eyes open for these intricate web-weavers, and admire their distinctive features and stunning patterns.

Habitat and Distribution

The Spined Micrathena is an orb-weaving spider that can be commonly found in hardwood forests throughout the eastern United States. For example, these spiders can be seen thriving in states like North Carolina and Missouri.

You may often spot them in the understory of forests, where they spin their intricate webs. Their webs are usually strategically built between shrubs and low branches, serving as perfect traps for their prey – different types of small flying insects.

At times, Spined Micrathena habitats can extend to nearby grasslands and suburban gardens. But they predominantly prefer hardwood forests since these areas provide them ample opportunities for web construction and abundant prey.

When considering the distribution of Spined Micrathena, remember that these spiders are typically more active during summer months. This means you’re likely to encounter them during their peak activity season, from June through September.

Life Cycle

The life cycle of the Spined Micrathena spider is quite fascinating. In late summer, typically around August and September, these spiders reach their adult stage. As the spider grows, it goes through several molts, shedding its exoskeleton to accommodate its larger size.

Throughout their life cycle, Spined Micrathena spiders exhibit diurnal behavior, meaning they are most active during the day. This is when they are likely to be seen spinning their intricate webs, which they use to catch their prey.

In the beginning of fall, the female Spined Micrathena will lay her eggs in a cocoon-like structure. She then spends her remaining days protecting the eggs until she dies. The spiderlings later hatch from these eggs to start the cycle anew.

When you encounter a Spined Micrathena spider, you’re likely to notice its unique appearance. Here are some characteristics to look for:

  • Distinctive shape with black-tipped spines
  • Typically black with white or yellowish markings
  • Female spiders are larger than the males

Spined Micrathena spiders can be found in various wooded areas and provide helpful pest control by capturing insects in their webs. Remember, they are harmless to humans, so if you see one, simply take a moment to admire their intriguing form and skills.

Web Construction

As a spined micrathena, you are an orb weaver spider known for creating intricate and well-constructed webs. Your orb-shaped webs are stunning examples of natural architecture. Here’s what you need to know about your web construction abilities:

Your webs are generally circular, resembling the classic wheel-shaped pattern associated with many orbweaving spiders. They are designed to be both functional and visually impressive, with concentric circles connected by radial lines.

Some key features of your webs include:

  • Wheel-shaped, circular design
  • Concentric circles connected by radial lines
  • Strong and sturdy construction
  • Ideal for capturing prey

Building a web requires patience and dedication. You start by constructing the main support lines, which are attached to nearby objects like tree branches and leaves. Then, you meticulously create the web’s radial lines from the center outward. After the radial lines are in place, you weave the concentric circles, starting near the center and working your way out.

Spined micrathena webs are not only functional but also beautifully designed. Elegance and efficiency go hand in hand when it comes to your web construction. Remember, your finely-crafted webs play a crucial role in your survival, as they help you catch a variety of insects to feed on.

So take pride in your web construction abilities and embrace your unique position as a spined micrathena, one of the most fascinating spiny orbweavers out there. Happy weaving!

Diet and Predators

Spined Micrathena spiders are known for their distinctive appearance, with the females having five pairs of black cones or spines on their abdomens. These spiders play an important role in nature, particularly in controlling insect populations, as their primary diet consists of various insects.

When it comes to predators, Spined Micrathena may fall prey to an array of creatures. For example, birds like vireos are known to feed on spiders. In general, some of the predators of Spined Micrathena include:

  • Birds (such as vireos)
  • Larger insects
  • Praying mantises
  • Wasps

These spiders contribute to the balance of nature by both keeping insect populations under control and serving as a food source for their predators. In doing so, they maintain a healthy ecosystem and contribute to the biodiversity of the habitats they occupy.

Gender Differences

In the world of Spined Micrathena spiders, there are noticeable differences between the females and males.

Females:

  • Females are typically larger and more striking in appearance than males.
  • The female Spined Micrathena has a unique look with a ten-spined, chunky abdomen1.
  • Their colors can vary from whitish to yellowish mottled with black or brown, and they have glossy black legs1.
  • Females are often the ones seen spinning intricate, circular webs2.

Males:

  • Males, on the other hand, are much smaller and less noticeable1.
  • They’re also not known for spinning webs like their female counterparts1.
  • Male Spined Micrathena spiders are not as visually distinct as females and are seldom seen1.

Despite these differences, both genders play an important role in the life cycle and survival of the Spined Micrathena. So, when exploring the world of these fascinating spiders, keep an eye out for both the impressive females and the elusive males.

Impact on Humans

You might be wondering if spined micrathena spiders pose any threat to humans. Good news: they are generally considered harmless. Here’s what you need to know about their impact on humans:

Bite and Venom:
Spined micrathena spiders do possess venom, like most spiders. However, their venom is mainly used to subdue and kill their prey, not for defense against humans. Their bite is generally harmless to humans, causing only mild pain and temporary redness, if at all1.

Hikers and outdoor enthusiasts will sometimes come across spined micrathena spiders, particularly in wooded areas3. It’s not uncommon to walk into their webs, but don’t worry—they’re not aggressive, and any bites are likely accidental and result from the spider feeling threatened.

In summary, spined micrathena spiders may look intimidating with their spiny abdomens, but they are actually not dangerous to humans. So, next time you encounter one, there’s no need to panic. Instead of fearing these fascinating creatures, appreciate their unique appearance and role in your local ecosystem.

Specific Species

Spined Micrathena spiders belong to the genus Micrathena and are known for their distinct appearance and spiny abdomens. In this section, we’ll look at three types of Spined Micrathena spiders: Micrathena gracilis, White Micrathena, and Spiny-bellied Orbweaver.

Micrathena gracilis is the most commonly encountered Spined Micrathena in Missouri. Its abdomen is mottled with white and black or yellowish and brown-black. This species has five pairs of black tubercles on their abdomen, giving them a unique look source.

The White Micrathena is another species with two short pairs of tubercles, and a white abdomen featuring a few distinct black blotches on the upper side source. The scientific name, mitrata, refers to its appearance, which resembles a turban.

The Spiny-bellied Orbweaver is not specifically mentioned in the search results, but it is likely another common name for the Micrathena gracilis, due to its spiny abdomen and orb-weaving behavior.

Comparing these three species, we can see some key differences:

Feature Micrathena gracilis White Micrathena
Abdominal tubercles 5 pairs of black tubercles 2 short pairs of tubercles
Coloration White and black or yellowish and brown-black White abdomen with black blotches

Here are some characteristics of Spined Micrathena spiders:

  • Unique spiny abdomens
  • Orb-weaving behavior
  • Typically found in woodlands and forests
  • Harmless to humans

As you explore the fascinating world of Spined Micrathena spiders, remember their unique features and the different species that make them stand out.

Copulatory Behavior

Spined Micrathena spiders exhibit unique copulatory behavior. Their mating process involves the use of specialized structures called palpal bulbs on the male spider. These structures are used to transfer sperm to the female during copulation.

Males of this species are seldom seen as they are much smaller and do not spin webs like females. They usually approach the female on her web, and begin courtship rituals to get her attention. A successful courtship can lead to the mating process where the male inserts his palpal bulb into an opening on the female’s abdomen called the epigyne.

During copulation, the sperm is stored in a specialized structure called a sac within the female’s abdomen. This sac can hold the sperm for a while before the female lays her eggs, allowing her to fertilize the eggs when she is ready.

To give you a better understanding, here are some key points related to Spined Micrathena copulatory behavior:

  • Males use specialized structures called palpal bulbs for sperm transfer.
  • Courtship rituals are performed by the male before mating.
  • Females store sperm in a sac within their abdomen.
  • Fertilization of eggs occurs when the female is ready to lay them.

In conclusion, the copulatory behavior of Spined Micrathena spiders is quite unique among the arachnids, involving specialized structures and interesting courtship rituals.

Footnotes

  1. Missouri Department of Conservation – Spined Micrathena 2 3 4 5 6

  2. Missouri Department of Conservation – Arrowshaped Micrathena

  3. Spined Micrathena | Arthropod Museum

Reader Emails

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

Letter 1 – Spined Micrathena

 

Spiny Spider
July 13, 2009
Found this guy in my hair yesterday (July 12) during a hike. I’ve never seen a spider like this. My husband didn’t believe it was a spider until it spun its silk to drop off a branch. Still not sure what type of spider it is. Sorry for the quality. We didn’t have our good camera on the hike. 🙁
Resa
Atlanta, GA

Spined Micrathena
Spined Micrathena

Hi Resa,
This is a Spined Micrathena, Micrathena gracilis, one of the orb weaving spiders.  It ranges over much of eastern North America.  We are amused with your comment about the picture quality, and we can only imagine the resolution of your good camera seeing as so much that we receive are either low resolution images taken with cell phones, or blurry large files taken by people who have no idea how to properly focus their cameras.

Letter 2 – Spined Micrathena

 

Black horned spider
October 6, 2009
This beauty is spinning away in my side yard. She has a preportionally huge black abdomen with horns and light colored markings on it. The underside is cone-shaped and ridged.
Jennnifer In Nyack
Nyack, NY

Spined Micrathena
Spined Micrathena

Dear Jennifer,
Your spider is a Spined Micrathena, Micrathena gracilis, a harmless Spiny Orbweaver.

Letter 3 – Spined Micrathena

 

Subject: spider in my backyard
Location: burton michigan
August 26, 2013 5:49 pm
I hope you can help me out by telling me what kind of spider this is I have about 7 of them in my backyard
Signature: jim mogie

Spined Micrathena
Spined Micrathena

Hi Jim,
We matched the color pattern of your Spined Micrathena,
Micrathena gracilis, a highly variable species, to this photo on BugGuide.  Your photograph, with its bold color pattern and astute division of space, is very beautiful.

Letter 4 – Spined Micrathena

 

Subject: Spider-like bug with a “skirt”
Location: Northern indiana
August 11, 2014 1:49 pm
We live in northern Indiana. We found what at first glance looked like a spider, but upon closer inspection appears to be an insect. It even behaved like a spider, running gracefully along a web. These photos were taken on August 11, 2014 around 5:00 pm. The bug was about a half inch long. I would love to know what it is.
Signature: Louann

Spined Micrathena
Spined Micrathena

Hi Louann,
This is a Spiny Orbweaver in the genus
Micrathena, commonly called the Spined Micrathena, Micrathena gracilis.  You can compare your image to this image on BugGuide.  According to BugGuide:  “Females are mostly white or pale yellow, mottled with black or brown. They have ten spines on the chunky abdomen. Size 8 – 10 mm.”  Your individual is a female.  She is perfectly harmless to humans. 

Thank you so much! I’ve never seen one before!

Letter 5 – Spined Micrathena from Mexico

 

What kind of spider is this?
Wed, Oct 15, 2008 at 8:03 AM
I found these two similar spiders on different sides of my house spinning traditional circular webs.
David Brownell
Lake Chapala, Mexico

Spined Micrathena
Spined Micrathena

Hi David,
What a gorgeous photo of a Spined Micrathena, Micrathena gracilis. In addition to Mexico, this species is also found in much of North America.

Letter 6 – Spined Microthena

 

Subject: What is this bug?
Location: New Hope, AL
July 8, 2012 9:58 pm
Saw this insect on a spider web outside of my house. Can you please tell me what it is?
Signature: Liz S

Spined Microthena

Hi Liz,
We do not see an insect in the orb web.  We do see the spider that made the web.  This is a Spined Microthena,
Microthena gracilis, and she is a female.  The males are much smaller and have fewer spines.  You can see additional photos and get some additional information on Bugguide.

Letter 7 – Two Spined Spider from Australia

 

How can something be so pretty and so creepy at the same time?
Location: NSW, Australia
December 2, 2011 2:08 am
Hi! I live in NSW, Australia, neer the coast. I found this multi coloured, spikey looking spider. You can’t see too well in the photos, but it was also red underneath. I live in the bush and I’ve seen lots of spiders, but never one so pretty! Can you tell me what kind it is?
Thank you.
Signature: Emma

Two Spined Spider

Dear Emma,
We had a power outage at our offices that lasted 36 hours.  This is a Two Spined Spider,
Poecilopachys australasia, and you can read some good information on Spiders on the Insects of Brisbane website.

I’ve always wanted to send something in to Whats That Bug! I waited untill I found something interesting that I’d never seen before. Can’t wait to find out more on the Insects of Brisbane website. Thank you so much!!! 😀

Letter 8 – Two Spined Spider from New Zealand

 

weird spider in NZ
Hello from New Zealand,
You may not be able to help, but if you can that would be wonderful. My husband and I discovered this spider in our garden today and captured it to take a photo. I just couldn’t get a very good photo. The white spots are actually points – like tiny volcanos, and are black on the back, outlined in red. Eyes, perhaps? The back half of the body is bright yellow. It has 8 legs, but appears to have 2 extra tiny legs when it walks that are on a very tiny body at the base as in Spider 2. The legs seem to mainly go to the front of the body as in Spider 1. Have you any clue about what it is? Thanks a lot for your thoughts.
Nancy and Hugh Mills

Hi Nancy and Hugh,
Back in December of 2005, we got our first image of this species, and with the assistance of a reader in January of 2007 when we received another image, it was properly identified as a Two Spined Spider, Poecilopachys australasiae. We also have a link with additional information that indicates the species is native to Australia but was introduced to New Zealand in the 1970s. This spider is often found on citrus trees.

Broken Links Fixed
Broken links on your site
December 28, 2010 4:53 pm
Hi,
You have a couple of links to Te Papa’s website on your website, thanks heaps for that! I have recently noticed in our logs that some of these are broken, so I thought I’d report them to you to enable you to fix them.
These broken links came from a data migration when we upgraded our website. We are really sorry about it.
These are the 3 pages with broken links:
http://whatsthatbug.com/2007/12/29/two-spined-spider-from-new-zealand/
http://whatsthatbug.com/2005/12/21/two-spined-spider-new-zealand-spiny-orb-weaver/
http://whatsthatbug.com/2007/01/17/spiny-orb-weaver-from-new-zealand/
The new address of the two-spine spider on our website is the following:
http://www.tepapa.govt.nz/ResearchAtTePapa/Research/NaturalEnvironment/InsectsSpidersAndSimilar/SpidersWeb/What/Pages/Twospined.aspx
Thanks a lot for linking to us again!
Kind regards,
Florence Liger, webmaster at Te Papa
Signature: Florence Liger

Letter 9 – Two Spined Spider from New Zealand

 

Subject: Spider identification needed!
Location: Wanganui, New Zealand
February 9, 2016 7:15 pm
My mother found this spider in the garden today and I was curious what type it is, any help would be appreciated!
Signature: Tessa Mitchell-anyon

Two Spined Spider
Two Spined Spider

Dear Tessa,
This little beauty is a Two Spined Spider,
Poecilopachys australasia, and according to T.E.R.R.A.I.N.:  “The nocturnal two spined spiders is an immigrant from Australia and have been recorded in New Zealand since the early 1970s. The female Poecilopachys australasia is about 9 mm in length and when mature has two white horn-like ‘spines. Yellow and white bands and some red-brown markings are visible. Large body hairs on an adult female gradually disappear as she approaches maturity. The two spined spider is found in gardens on shrubs, often on citrus trees. By day, the spider will hide under leaves, emerging at night to construct a cart wheel-shaped web.
The egg sac of the two spined spider is spindle shaped.  The male is much smaller (2.5 mm – 3 mm in length) and looks very different. . Adult males lack the pair of large abdominal spurs and the bright colours that characterize the adult females. They look so different that they were first thought to be a different species.  Despite the small size of the two spined spider, it is capable of capturing moths and other insects several times its own size. Two spined spiders are regarded as harmless to humans.”

Authors

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  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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2 thoughts on “Spined Micrathena: Essential Guide for the Curious Observer”

  1. Hi. Great site. I’d like to suggest that you put your statement regarding not endorsing extermination in larger letters, because it gets almost obscured by the huge exterminator ad that appeared underneath it. People may miss it and get the wrong idea.

    Reply
    • Thanks for the suggestion. Anyone who reads any of our content knows that we do not endorse extermination, but we do need the assistance of advertisers to defer the cost of bandwidth and related expenditures. Naturally, an insect website is a logical place to advertise for exterminators, and many people visit our site to have problematic insects like cockroaches, bed bugs and termites identified. Throughout all of that, our mission remains to educate people about the wonders of the natural world and to promote an understanding of the interconnectivity of the web of life in the world we share with the lower beasts.

      Reply

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