northern crab spider

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 male is much smaller, ⅛″ (3.5 to 4 mm) in length with a legspan of ¼″ (6 mm) or more. 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 (ALE), are a little larger than the interior eyes, the anterior median eyes (AME). In the back row the posterior lateral eyes (PLE) 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.

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 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.

Female Body Length: ¼″ (6 to 7 mm)

Male Body Length: ⅛″ (3.5 to 4 mm)

Legspan: ¼″ to ½″ (6 to 12 mm)

No web

Meadows, fields, roadsides, and gardens

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.

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.

Sources

24, 27, 29, 30, 82, 83.

Common

Genus
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.

Higher taxa
A recent molecular phylogenetic study (Benjamin et al., 2008) recovered four well-developed lineages within the family Thomisidae. The lineages are clades, and they do not correspond to any of the previously accepted subfamilies. The subfamily Thomisinae, and all other subfamilies, are eliminated.

A later phylogenetic analysis of the order Araneae (Wheeler et al., 2017) presented a new spider tree of life based on mitochondrial and nuclear genomes. The number and arrangement of the ranks and clades between the Order Aranae and the Family Thomisidae vary depending on the source. The superfamily Thomisoidea is eliminated. Araneomorphae is treated as an suborder by some sources, some rank Opisthothelae as the suborder and Araneomorphae as the infraorder, and some have Araneomorphae as the infraorder and no suborder. Opisthothelae is sometimes treated as an unranked clade, but it is more often omitted entirely. Most treat Entelegynae as an unranked clade, with two more unranked clades above (basal to) the Family Thomisidae. Some or all unranked clades are often omitted from taxonomic trees.

The ranking on this page follows iNaturalist.

Northern Crab Spider with its lunch a...

Yellow Jacket Wasp. I was surprised it could kill a wasp. Also it could just pick it up and lift it above its head and carry it up the lead plant.

Strong little spider. Came across these two northern crab spiders at Frenchman’s Bluff SNA recently. I’ve never really been into spiders, but these small crab spider species are really interesting and some are nicely colored and quite cute since they are so small. They spook easy as they often scooted under the flower if I approached to suddenly. Even the one with the wasp. It moved and hid behind the lead plant blossoms. I had too slowly and quietly move around to see what it was and what it was doing. I photographed and filmed them since not much else was going on out there and they were interesting little spiders. … the wild rose blossom wasn’t very big either was the spider.

… here is another Northern Crab with its dinner looks like some kind of a damsel fly or similar. That one was at the same area on 7-7-22. It is just a shrunk down 4k frame grab.

…I shot this picture of blood root and after taking the photo discovered there was some kind of a spider or insect on it with wicked looking legs. Could you tell me what kind it is?

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 vs Yellow Jacket Wasp" filmed by Dan W Andree
Jun 9, 2023

Northern Crab Spider catching and disposing of prey (Mecaphesa asperata)
Nature in Motion

Location: Albany, NY

Location: Albany, NY

Location: Albany, NY

Location: Albany, NY

Location: Albany, NY

Location: Milaca, MN

Location: Norman Co. Mn.

… here is another Northern Crab with its dinner looks like some kind of a damsel fly or similar. That one was at the same area on 7-7-22. It is just a shrunk down 4k frame grab.

Location: Frenchman’s Bluff SNA

Yellow Jacket Wasp. I was surprised it could kill a wasp. Also it could just pick it up and lift it above its head and carry it up the lead plant.

Strong little spider. Came across these two northern crab spiders at Frenchman’s Bluff SNA recently. I’ve never really been into spiders, but these small crab spider species are really interesting and some are nicely colored and quite cute since they are so small. They spook easy as they often scooted under the flower if I approached to suddenly. Even the one with the wasp. It moved and hid behind the lead plant blossoms. I had too slowly and quietly move around to see what it was and what it was doing. I photographed and filmed them since not much else was going on out there and they were interesting little spiders. … the wild rose blossom wasn’t very big either was the spider.

Location: just west of Houston, MN

Location: Big Willow Park, Minnetonka, Minnesota

I shot this picture of blood root and after taking the photo discovered there was some kind of a spider or insect on it with wicked looking legs. Could you tell me what kind it is?

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.