northern crab spider

(Mecaphesa asperata)

Conservation Status
northern crab spider
Photo by Margot Avey
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

     
  Minnesota

not listed

     
           
           
           
           
           
           
           
 
Description
 
 

Northern crab spider is a small spider. It occurs in the United States, southern Canada, and Mexico. In the United States it is common to very common in east, less common in the west. It is found on grasses, flowers, and foliage in meadows, fields, roadsides, and gardens. It is one of several spiders called “flower spiders” because it waits in ambush in flowers often for hours at a time.

The female is ¼ (6 to 7 mm) in length and has a legspan of up to ½ (12 mm). It is hairy and there are numerous spines and bristles on the body and legs. The plate (carapace) covering the front part of the body (cephalothorax) is flat and as long as wide. It is brownish-yellow to pale green with two dull, reddish-brown, longitudinal stripes. The abdomen is flat, broadly oval, and widest near the rear. It is often yellow with reddish-brown markings, but the background color can change to white or pale green to blend in with the vegetation. On the front half of the abdomen there is a central stripe and two lateral stripes. On the back half, behind the central stripe, there are two rows of closely-spaced spots converging at the rear of the abdomen and forming a capped V shape.

The male is much smaller, (3.5 to 4 mm) in length with a legspan of ¼ (6 mm) or more.

The legs are pale with pinkish or reddish bands on the fifth segment (tibia) and the sixth segment (metatarsus). The front two pairs of legs are thicker and much longer than the others, and are normally held out and forward, like a crab. This is the feature that gives the family Thomisidae its common name. There is a pair of minute claws at the end of the legs but these are not visible without magnification.

There are eight eyes arranged in two curved rows of four. All of the eyes are on low raised projections (tubercles). In the front row the outermost eyes, the anterior lateral eyes (ALEs), are a little larger than the interior eyes, the anterior median eyes (AMEs). In the back row the posterior lateral eyes (PLEs) are directed sideways and backwards. They are not visible when the spider is viewed from the front. The jaws (chelicerae) are small and have no teeth.

 
     
 

Size

 
 

Female Body Length: ¼ (6 to 7 mm)

Male Body Length: (3.5 to 4 mm)

Legspan: ¼ to ½ (6 to 12 mm)

 
     
 

Similar Species

 
     
     
 
Habitat
 
 

Meadows, fields, roadsides, and gardens

 
     
 
Biology
 
 

Season

 
 

 

 
     
 

Behavior

 
 

When the legs are held out to the side, the spider is able to walk forward, backward, or sideways (laterigrade).

When hunting, the spider will sit, often in a flower and often for hours, waiting in ambush for prey.

The female does not build webs, snares, or retreats. To protect its egg sac it will fold over the edge of a leaf and secure it with silk.

 
     
 

Life Cycle

 
 

The male is tiny compared to the female. To mate without first being eaten, it must first tie up the female with silk. After mating, the female easily breaks the restraints.

 
     
 

Food

 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

24, 29, 30, 82.

 
  8/16/2021      
         
 

Occurrence

 
 

 

 
         
 
Taxonomy
 
  Class Arachnida (arachnids)  
 

Order

Araneae (spiders)  
 

Suborder

Araneomorphae (true spiders)  
 

Superfamily

Thomisoidea (crab and running crab spiders)  
 

Family

Thomisidae (crab spiders)  
 

Genus

Mecaphesa  
       
 

Until recently, almost all species currently in the genus Mecaphesa were placed in the genus Misumenops. In 2008 almost all of the North American Misumenops species were transferred to Mecaphesa.

 
       
 

Synonyms

 
 

Misumenops asperatus

 
       
 

Common Names

 
 

northern crab spider

northern flower crab spider

 
       

 

 

 

 

 

 

 

 

Glossary

Carapace

The hard, upper (dorsal), shell-like covering (exoskeleton) of the body or at least the thorax of many arthropods and of turtles and tortoises. In crustaceans, it covers the cephalothorax.

 

Cephalothorax

The front part of a spider’s body, composed of the head region and the thoracic area fused together. Eyes, legs, and antennae are attached to this part.

 

Chelicerae

The pair of stout mouthparts, corresponding to jaws, in arachnids and other arthropods in the subphylum Chelicerata.

 

Tibia

The fourth segment of an insect leg, after the femur and before the tarsus (foot). The fifth segment of a spider leg or palp.

 

Tubercle

On plants and animals: a small, rounded, raised projection on the surface. On slugs: raised areas of skin between grooves covering the body.

 

 

 
 
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Margot Avey

 
 

Spider and flower

This photo was taken in St Paul Park, Minnesota by my friend Julie. She has given the okay to send it to you.

Interesting flower and matching spider! We have no idea what kind of spider it is.

  northern crab spider  
           
 
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Other Videos
 
  Northern Crab Spider catching and disposing of prey (Mecaphesa asperata)
Nature in Motion
 
   
 
About

Oct 26, 2016

This beautiful spider should win an Academy Award.

Arachnida (Arachnids) » Arachnids (Spiders) » Araneomorphae (True Spiders) » Entelegynes » Thomisidae (Crab Spiders) » Mecaphesa » Mecaphesa asperata (Northern Crab Spider)

Music: Pina Colada

 
       

 

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  Margot Avey
7/21/2021

Location: St. Paul Park, Minnesota

This photo was taken in St Paul Park, Minnesota by my friend Julie. She has given the okay to send it to you.

Interesting flower and matching spider! We have no idea what kind of spider it is.

northern crab spider  
           
 
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Created: 8/16/2021

Last Updated:

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