The common name crab spiders brings to mind an arachnid with a round body that mimics the look of a crab. That initial visual serves as a generally good physically descriptive starting point for three North American spider families that have crab spider as a common name.
In most residential areas of North America, the crab spider (family Thomisidae) genera represent the typical crab spider. Thomisidae share physical characteristics such as round bodies, short legs, and a tendency for side to side movement. Some, but not all Thomisidae species also go by the nickname flower spiders.
There’s a high probability that at least one flower spider species inhabits the average backyard flower garden.
Crab Spider Pictures
Species from the three most common crab spiders genera, Misumena, Misumenoides and Misumenops, are presented for identification.
Goldenrod Crab Spiders
The name flower spider formally applies to the Goldenrod Crab Spider (Misumena vatia). Females are typically three times larger and consequently receive more noticed than the male. They normally have either yellow or white bodies with a stripe around the abdomen.
Whitebanded Crab Spiders
Picture two, the Whitebanded Crab Spider (Misumenoides formosipes) highlights the fact that color name does not always apply. Apart from the eye pattern. the stripes on the top of the head portion of the body and the symmetrical pattern on the abdomen are good field identification marks. The body color and pattern for females can be yellow and red, as in the top picture, or yellow and black, white and black or white and red. Males are significantly smaller and often two sets of very dark front legs.
Hairy Crab Spiders
Misumenops, also called the Hairy Crab Spider often have a white or yellow body. They somewhat resemble the whitebanded crab spiders, however their bodies are hairy.
No crab spider builds a webs, rather they rely on their small size and color to hide on either flowers or plants (depending on their body color) waiting for their potential prey to visit. The duller color species sit close to the ground or on bark or branches.
Identifying crab spider species, at least to the level of genus, can be done by close observation of some physical characteristics, including eye patterns. Many hunt on flowers and shrubs in residential areas, making them easy to find.
Running Crab Spiders
Running Crab Spiders (family Philodromidae), the second family subsumed under the common crab spider name, could be considered the forgotten crab spiders. Leg size differentiates the families with the running crab spiders having longer second pair of legs. The size difference becomes readily apparent in either a real life or a picture comparison
In comparative terms, less color variation in running crab spiders correlates nicely with their need for less camouflage when hunting compared to the camouflage needs of flower spiders.
Apart from the physical difference, both families are hunting spiders, albeit with different hunting strategies. Running crab spiders, more often than not, tend to chase prey while crab spiders (flower spiders), more often than not, tend to perch typically on flowers and leaves, and wait for prey. Of course there are variations to these general rules. It’s not impossible, for example, to find a running crab spider sitting on top of a flower.
Giant Crab Spiders
The name speaks for itself. Giant Crab Spiders, family Sparassidae, can grow up to four inches in length. A few introduced species inhabit the warmer areas of North America, including Florida and Hawaii.
They also go by the name huntsmen spiders, and their above average size along with their propensity to wander into residences and cars, often causes extreme bouts of anxiety to the average arachnophobe who crosses paths with it.
All spiders bite, including Sparassidae. However, they are not listed as a spider of medical concern.