Are crab spiders poisonous?

| December 8, 2020

Crab spiders are one of the species belonging to the family of Thomisidae. They are short and wide-bodied animals. They have a flat body, bearing four pairs of legs. The first pair of legs are more developed and more prominent than the other three pairs. They usually walk backwards or sideways, and while walking, they only use their legs at the back. Due to this, they are called crab spiders.

All crab spiders have eight eyes, which help them to see in all directions. The male and female species are usually in different colours, and females are comparatively larger than the females.

What is a crab spider?

There are many spiders in the world belonging to different families and exhibiting various features. One of them is a crab spider. It belongs to the family of Thomisidae and order Araneida. The family of Thomisidae contains many species that can be seen worldwide, including species that live on leaf litter, on soil, or under the tree barks. Around 125 species of the family of Thomisidae are found in the USA alone. They are mostly found in the areas of North America and Canada.

Are crab spiders poisonous?


  • The body of the crab spider is 12mm long. The body of the female species is longer than the male species. It has a broad flat body with four pairs of legs. The first front pair of legs are more developed and longer than the other three pairs. It also has eight eyes, which help it to see in all directions.
  •  It is white, grey, or brown, but interestingly, they can change their body’s colour according to their environment.
  • It is called crab spider because its body is crab-shaped and because of its ability to walk side-ways and backward like a crab.
  • The crab spiders are most active during the day and not at night, so that we can call them “Diurnal animals.”
  • They love to live in gardens, tropical rainforests, meadows, grasslands, marshes, and scrublands. They prefer flowers which are yellow and white. They avoid habitats like icy places like cold mountainous peaks and dry areas like deserts.
  • Crab spiders can survive one or two years, depending on the environment.


The mating season of crab spiders usually takes place in summer. Men follow silk threads to find women. They put the semen bags on the ground. Females collect these bags with legs called “tentacles” and fertilise the eggs.

Crab spider Bite

Spider crabs are hunters and ambush planters. Some species sit on or among flowers, under tree barks, fruits, or leaves, where they attack the visiting insects. They use their bigger and more powerful front legs to grab and hold prey, paralysing it with a poisonous bite. Due to this reason, some insects avoid visiting flowers and fruits, which are used by crab spiders as their deadly traps. They like to trap butterflies, flies, and honeybees because these are their favourite foods.

The bite of the crab spider is venomous for insects, but they hardly damage the human body. They can bite human beings only for the sake of their self-defence.

Although, crab spiders are a favourite prey of wasps, giant spiders, ants, lizards, and birds.

Crab spider poison

Like other family members, crab spiders can bite us and can leave two small puncture holes on the skin by using their fangs. They use their fangs to transfer their venom into the human body. The crab spider’s venom is deadly enough to kill its enemy smaller or somewhat more prominent than the crab spider’s size, but it is hardly dangerous to the human body. This is because they are generally too small for this, and they are very non-aggressive, but the bite of more massive spiders can be painful.

Crab spiders bite treatment

Since crab spiders are very timid and non-aggressive, they are hardly seen to bite any human until they are provoked. They might attack humans when they see themselves in a difficult situation and then try to defend themselves by using their fangs placed on the body’s front. Their bite is not as harmful as the bite of many other spiders larger than the crab spider.

White spiders are harmless to humans. Their bite is not poisonous to people, and there are no side effects at all. If a crab spider has bitten you, you may have a painful sensation initially, but it will vanish in no time. So there is no need for any treatment after the bite of a crab spider.

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