Do Crab Spiders Bite? Unraveling the Mystery

Crab spiders are small to medium-sized spiders that can be found in various habitats, such as gardens, fields, and forests. They have a unique appearance with the first four legs being longer than the back four and held out to the sides, giving them a crab-like appearance. These spiders come in different colors, ranging from yellow or red to brown or gray, and some species even have the ability to change color, like the Goldenrod Crab Spider, which can produce or excrete a yellow pigment depending on its surroundings 1.

When it comes to the topic of spider bites, it is important to note that most spiders rarely bite people, and many of them are harmless. Crab spiders, in particular, are generally considered non-aggressive and pose little to no threat to humans 2.

Crab Spider Identification and Appearance

Physical Features

Crab spiders belong to the family Thomisidae, with over 2,000 species found globally, and many residing in North America. These arachnids have a distinct and unique appearance.

  • Eight eyes
  • Eyes on raised bumps for better vision in various directions1
  • Round body
  • Crab-like legs
  • Size varies depending on the species2

Coloration and Camouflage

Crab spiders are known for their remarkable coloration and camouflage abilities.

  • Bright, vibrant colors to blend with flowers3
  • Ability to change color depending on their surroundings
  • Effective ambush predator

For example, flower crab spiders’ coloration allows them to blend in with their environment, making them nearly invisible to both prey and predators.

Crab-Like Appearance

These spiders receive their name from their notable crab-like appearance.

  • Regulated front legs allowing sideways movement4
  • No silk web, unlike other spider families
  • Leg shape and positioning resemble that of a crab

Crab Spider Behavior and Habitat

Ambush Predators

Crab spiders, belonging to the Thomisidae family, are known for their unique hunting style and crab-like appearance. They are ambush predators that use their camouflage skills to blend in with their surroundings, usually on flowers or leaves, and wait for prey to approach.

Diet and Prey

Their diet primarily consists of insects such as flies, bees, and butterflies. Crab spiders don’t use silk to build webs; instead, they rely on their excellent camouflage and swift movements to catch their prey. For example, the Goldenrod Crab Spider (Misumena vatia) can change its color from yellow to white to blend in with flowers.

Beneficial Role in Pest Management

Crab spiders have a beneficial role in pest management as their feeding habits help control insect populations. As natural predators, they keep a check on infestations and play a crucial role in maintaining a balanced ecosystem.

Habitat and Distribution

Crab spiders are widely distributed across various habitats. Some genera, such as the flower crab spiders (family Thomisidae), prefer to live on flowers and leaves of plants. In contrast, the giant crab spiders (family Sparassidae) and members of the Philodromidae family inhabit more diverse environments.

Comparison table: Flower Crab Spiders vs. Giant Crab Spiders

Features Flower Crab Spiders Giant Crab Spiders
Habitat Flowers, leaves Diverse environments
Camouflage Excellent Varying
Size Small to medium Larger
Prey Insects Insects, other spiders

In conclusion, crab spiders show fascinating behaviors, such as ambush predation and camouflage, and play an essential role in pest management. Their wide distribution and diverse habitats make them a fascinating group of spiders to study.

Crab Spider Reproduction

Mating Process

Crab spiders belong to the Thomisidae family and are known for their crab-like appearance and movements. The mating process involves the male crab spider approaching the female cautiously, with their size being usually smaller than the female. The male transfers sperm to the female using his swollen pedipalps, which are specially adapted for this purpose.

Egg Laying and Silken Egg Sacs

Once the mating process is complete, the female crab spider lays her eggs. Some common examples of crab spider species found in North America include the flower crab spiders (Thomisidae) and the widow spiders (Sicariidae). Female crab spiders use their silk-producing abilities to create silken egg sacs, which help protect the eggs from predators and weather conditions.

Characteristics of silken egg sacs:

  • Made of silk
  • Provide protection for eggs
  • Can vary in size and shape depending on the species

Hatching and Spiderlings

The hatching time of crab spider eggs varies depending on the species and environmental conditions but typically occurs within a few weeks. Upon hatching, the baby spiders, known as spiderlings, emerge. These spiderlings go through several molts as they grow, shedding their exoskeleton to allow for expansion.

Spiderling features:

  • Hatch within weeks
  • Go through several molts to grow
  • Resemble miniature adult spiders

Crab Spider Bites and Treatment

Venom and Bite Effects

Crab spiders are not considered to be harmful to humans. While they can bite, their venom has minimal impact on people. Symptoms of a crab spider bite may include:

  • Itching or rash
  • Pain radiating from the bite site

Recognizing a Crab Spider Bite

Identifying a crab spider bite can be difficult, as the bite might look like other insect bites. However, you can try to recognize it by looking for some of the mentioned symptoms, such as itching or rash, and pain around the site.

First Aid and Treatment

If you think you’ve been bitten by a crab spider, following these first aid steps can help alleviate the discomfort:

  1. Wash the area with soap and water
  2. Apply an ice pack or wet compress
  3. Consider over-the-counter pain medicine if needed
  4. Use antihistamines for severe swelling (source)
Crab Spider Bite Symptoms Recommended Treatment
Itching or rash Wash with soap and water, apply an ice pack or wet compress
Pain at bite site Over-the-counter pain medicine, ice pack or wet compress
Severe swelling Antihistamines

Keep in mind, crab spider bites are not usually a cause for concern; however, if you experience severe symptoms or if the bite does not improve, it’s essential to seek medical advice.

Footnotes

  1. Biokids – Thomisidae Information
  2. Wikihow – Identifying Crab Spiders
  3. Columbian – The Camouflage of Crab Spiders
  4. World Spider Catalog – Thomisidae

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 – Crab Spider

 

white spider
Hi! I live in Pennsylvania. I found this spider crawling around on my butterfly bush a couple weekends ago. It kinda freaked me out because I’ve NEVER seen one like this! I usually don’t mind spiders, but this guy is creepy! What is it????? Thanks!
Billiejo

Hi Billiejo,
This is a Crab Spider, most probably Misumena vatia, also known as a Flower Spider because if waits in flowers for pollinating insects. They are capable of changing colors to match their surroundings.

Correction from Eric Eaton (09/13/2007)
Hi, Daniel:
The white “crab spider” of 9/11 is indeed a crab spider, but it is not Misumena vatia. It is Misumenoides formosipes. Hey, I get confused, too!
Eric

Letter 2 – Crab Spider

 

Insect seen on Buford Mountain, Missouri
Location:  Buford Mountain, Missouri
September 6, 2010 8:24 pm
I captured this insect on Buford Mountain in Southern Missouri. It was very odd and I decided to shoot a picture.
Signature:  John Tehan

Whitebanded Crab Spider

Hi John,
This is not an insect.  It is a Crab Spider in the family Thomisidae.  It appears to be a female Whitebanded Crab Spider,
Misumenoides formosipes, a highly variable species that is well represented on BugGuide with photographs documenting its numerous color variations.  Crab Spiders often wait on flowers to ambush pollinating insects that alight without noticing the well camouflaged spiders.

Thank you so much!
This was truly an amazing looking spider. I am glad to know what it really is.
It does look like a crab.
Thanks again.
John

Letter 3 – Crab Spider

 

Not Miss Scarlett, Hiding in the Drapery…
Location: Coryell County, Central Texas
October 27, 2010 8:55 pm
… but perhaps Mr. Marbled Orb Weaver, hiding in the roses. I’ve been looking for the mister for two years; we see the missus often, she’s quite the show-off. Are these marbled orb weavers?
Signature: Ellen

Crab Spider

Dear Ellen,
You have two different species of spiders and we are posting your awesome images of a Crab Spider, but not the Orbweaver.  Crab Spiders look like and move like crabs, but they also wait on blossoms to pounce upon nectaring insects, so they are also called Flower Spiders.  We are having a problem identifying your species on BugGuide, but it does seem to resemble this unidentified individual from Florida posted on BugGuide.

Crab Spider

Letter 4 – Crab Spider

 

Acting Crabby!!

Crab Spider

Acting Crabby!!
Location: Mid-Missouri
October 28, 2010 9:36 am
I found this green crab spider in a section of my yard that has a lot of insect activity. I have no doubts that this crab ended up with a nice meal. When I noticed her she was being pretty active which made it difficult to get any good images, but she did stop for a few brief moments. There was one time when I got a little too close that she made a move for me (for my camera actually), but overall, she was more than accommodating at ME being the pest.
I’m not too sure on my ID. Looking at the guide, the closest I can find is Misumessus oblongus, but there are discrepancies in all of the guide images I see. Mainly, the guide shows the head portion to be a greenish color with an opaque/white abdomen whereas mine has a more clear/opaque head with a whitish abdomen.
(The third image, while not as artistically perfect, shows a much better view of the body)
Signature: Nathanael Siders

Crab Spider

Hi Nathanael,
Thanks for submitting your beautiful images of a Crab Spider in the family Thomisidae.  We agree that it sure does resemble the images of
Misumessus oblongus that are on BugGuide.  Crab Spiders like many other spiders can be highly variable in coloration and markings which probably aids in the survival of the species through adaptation to different environmental conditions.

Crab Spider

Letter 5 – Crab Spider

 

Unknown Spider
Location: Central Maine
June 20, 2011 11:03 am
Found this guy on the rose bush out front without actually intending to. I just receved a new camera lens in the mail and was testing it out when this little guy (gal?) decided to make an appearance.
I thought I’d ID’ed it as a jumping spider, but the range is completely off as it was listed as Virginia to Florida – and I’m in Maine.
It was a fairly decent sized spider as well, maybe an inch or a bit less legtip to legtip.
Signature: Jody

Crab Spider

Hi Jody,
This is a beautiful photograph of a Crab Spider,
Misumena vatia, in the family Tomisidae.  All members of the family are known as Crab Spiders, so that common name is not especially specific.  Crab Spiders do not build webs to snare their prey.  They often wait in ambush and they are excellent camouflage artists.  This species is also commonly called a Flower Spider because they wait on blossoms to ambush prey.  This species is also found in numerous color variations, and spiders tend to choose blossoms that most closely match their own coloration.  Here is a photo from BugGuide that looks very much like your individual.

Letter 6 – Crab Spider

 

Subject: Crab Spider in Los Angeles? BONUS QUESTION
Location: Los Angeles, CA
August 17, 2012 4:10 pm
Hey Bugman. I wanted to show you a couple pix of a crab spider I found in my yard in Los Angeles. At least, I think it’s a crab spider. Can you please confirm?
BONUS: The third (and obviously different) photo is a black orb weaver – can you confirm too?
Signature: -Amy

Crab Spider: Misumenoides formosipes

Hi Amy,
Though it is highly variable in coloration according to BugGuide, we believe we have identified your individual as a White Banded Crab Spider,
Misumenoides formosipes, based on this image on BugGuide.  According to BugGuide:  “The identifying characteristic, according to Florida’s Fabulous Spiders, is a white ridge on the spider’s face below the eyes. Can be either white or yellow. Most sources say this is a response to its surroundings, but I did find one claim that color depended on whether the egg was laid on a yellow or white-flowered plant. See here for brief description of this theory.”  The theory, according to the Spiders of Kaweah River Delta Region by Marjorie Moody is:  “According to ‘Spiderman’ Brian Carroll, this flower crab spider cannot change its color like a chameleon. He performed an experiment and disproved the myth that this spider can change to white or cream if placed on a white flower. What he did discover, however, is that if a yellow crab spider lays her eggs on a white-flowered plant, her offspring will be white, not yellow. Furthermore, if a white crab spider lays her eggs on a yellow-flowered plant her offspring will be yellow, not white. ”  Crab Spiders do not spin webs to trap prey.  They often wait on flowers and plants to ambush insects that are attracted to the plants.  Though we cannot determine the species by your photograph, the other spider does appear to be an orbweaver.

Letter 7 – Crab Spider

 

Subject: brown recluse? crab spider? help.
Location: Atlanta GA area
December 4, 2013 8:12 pm
Hey guys. Hoping you can help me as I have 2 children in the home and hoping they arent in any danger of brown recluse spiders in my house.
Thanks yall are always amazing!!!!
Signature: Allison

Crab Spider
Crab Spider

Hi Allison,
This is most definitely NOT a Brown Recluse.  Because of the relative length of the two pairs of front legs, we agree that this is a Crab Spider in the family Thomisidae.

Letter 8 – Crab Spider

 

Subject: A yellow spider on Marin County’s Mount Tamalpais
Location: Mount Tamalpais, near Mill Valley, CA, USA
March 10, 2014 8:03 pm
I saw several of these small yellow spiders on leaves of Arctostaphylos glandulosa near the top of Marin’s Mount Tamalpais. Any idea?
Signature: S. R. Gilbert

Crab Spider
Crab Spider

Dear S.R. Gilbert,
This is a Crab Spider in the family Thomisidae.

Letter 9 – Crab Spider

 

Subject: Green spider
Location: San Francisco Bay Area
April 16, 2016 5:32 pm
What kind of spider?
Signature: Tad

Crab Spider
Crab Spider

Dear Tad,
This is a Crab Spider in the family Thomisidae, and members of the family can be identified because the front two pairs of legs are much longer than the other two pairs.  Your individual is Diaea livens, which we identified on BugGuideBugGuide only contains reports of the species from California.  Your image represents a new species on our site.

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 “Do Crab Spiders Bite? Unraveling the Mystery”

  1. I have one of these species right here in a jar in Virginia, He was on my arm moments ago. As expected we’re all going to look first to see if we’re doomed, After that we wan’t to know more of it. I can send pictures if you provide me an email address. I have high res macro shots.

    Reply

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