Insect Identification
Insect Identification

Black Tail Crab Spider - (Synema parvulum)

Authored By Staff Writer | Last Updated: 10/20/2014

What the Black Tail Crab Spider lacks in claws it makes up for with mighty jaws and a great work ethic.

Crab spiders have long front forelegs that sit more forward on the body. The back pairs of legs are so much shorter and further back than the front pairs that it gives them the appearance of the kind of crab found in the ocean, on a much, much smaller scale.

In addition to the typical Crab spider physique, this particular species has a black spot on the tip of the abdomen, as if their 'butts' (abdomen) were dipped in black ink.

The crab spider does not use a web to catch prey. They ambush insects, lying in wait inside or on flowers. They have also been found on wood or tree bark. The Black Tail Crab Spider will grab its insect prey and use its front legs to help pin the victim down. It then bites the prey with its strong jaws and immobilizes it for consumption.

Because this spider preys on insects that may damage plants and flowers (like aphids), it is considered helpful to the garden ecosystem.

The Black Tail Crab Spider is not known to bite humans as it takes little interest in their activity. Their venom is not poisonous to humans. Like most spiders, however, they will defend themselves if provoked, squeezed or threatened.

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Category: Spider
Common name: Black Tail Crab Spider
Scientific Name: Synema parvulum

  Kingdom: Animalia
   Phylum: Arthropoda
    Class: Arachnida
     Order: Araneae
      Family: Thomisidae
       Genus: Synema
        Species: parvulum

Adult Size (Length): 5mm to 7mm (0.20in to 0.28in)

Identifying Colors: brown; black; red

Additional Descriptors: crab, butt, legs, venomous, biting, helpful

North American Reach (Though Not Limited To*): Alabama, Arizona, Arkansas, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Mississippi, Missouri, Nevada, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, South Carolina, Tennessee, Texas, Utah, Virginia, West Virginia

* Keep in mind that insect reach is not governed by lines on a map and therefore may appear in areas/regions/states beyond those listed above.