Crab Spider

Closeup of a white crab spider on purple buddleia blossoms

Crab spiders actually belong to multiple spider species, but many of them are members of the spider family Thomisidae. The closest kind of spider species to the crab spider is the flower crab spider, which is known for ambush hunting while hiding in flowers.

Crab spiders are called such because of their resemblance to crabs and the manner of how they position their two front pairs of legs. Their ability to move sideways or backwards also got them the name crab spiders.

Doe crab spiders bite? The answer is yes. Crab spiders bite but they are not harmful to people. They only eat beneficial insects that pollinate plants.


Their front legs are larger and stronger than their six other legs, and are held sideways in a manner always ready to catch a prey.

They have excellent eyesight with the use of their big front eyes, and can move quickly towards their prey, making them effective hunters.

The size of a crab spider ranges from 4 to 10 mm. Female crab spiders usually guard their egg flat sacs which are attached to the vegetation. The smallest crab spider species measures about 2 mm and has a brown greenish color.

The Genus Bomis species is native in Australia mostly in Northern and Eastern Australia. The tiny spider usually hides in a bent leaf secured at this position by silk. This area also serves as its nesting area.

The Genus Cymbacka crab spider measures from 3 to 7 mm and usually hides in a rolled leaf. The males of this species are smaller than females.

The Genus Diaea crab spider is also known as flower spiders that measures from 5 to 7 mm. This species hides between vegetation usually near a flower and its color adapts to the surrounding.

The Genus Hedana crab spider is a small species which has a long narrow abdomen and lives between foliage, making it difficult to spot.

The Genis Poecilothomisus crab spider is an attractive spider with an orange body.

Those belonging to the Genus Runciania have long oval abdomens with long stripes and are abundant in Australia.


Crab spiders are commonly found throughout North America and Canada, and Australia.


Crab spiders’ favorite habitat are on gardens, meadows, fields, woods and shrubs. They prefer flower blossoms especially those that are yellow or white color.

Food and Hunting

Crab spiders are do not build webs to catch their prey but instead they produce silk drop lines. Others are hunters or ambush predators and use their front legs to catch a prey. The hunting crab spiders usually sit on or beside flowers or fruit and in the same area even for days and weeks where they wait and grab insects that settle on the flower or fruit.

Some species can change color over a few days in such a way to match color of flower where it sits while some species sit on leaves or bark where they wait for a prey. Crab spiders with flat bodies hunt in the crevices of tree trunks and some under the loose bark.

Leave a Reply