Flower Crab Spider

Crab spiders are abundant in my desert garden at home and can also be spotted out in the wadis. Belonging to the Thomisidae family of spiders, they earned their common name from the way they extend their front pairs of legs in a crab-like fashion.

Female Flower Crab Spider (Thomisus citrinellus) on a flower bud of a caper bush.

Flower crab spiders belong to the genus Thomisus and there are about 150 species worldwide. They earned their name from the fact that they are ambush predators, sitting and waiting motionlessly in or nearby flowers for prey to approach. Today, I will introduce you to the Flower Crab Spider Thomisus citrinellus.

Female Flower Crab Spider (Thomisus citrinellus) on horsemint (habaq) flowers.

Like all crab spiders, the males are much smaller and differently-colored than the females. Female spiders can vary in color – I’ve seen both yellow and white – and the color may depend or change according to the surrounding vegetation. They range from 5 – 7.3 mm in size, whereas males grow from 2.1 – 2.6 mm long. Females usually have dark spots on the points of their abdomens. The first two pairs of legs are longer and thicker and have spines. On the first pair of legs, there are four distinctive dark bristles, often seen as dots in the field. These dark bristles distinguish this from other similar Thomisus species.

Female Flower Crab Spider with a male riding piggyback.
Male Flower Crab Spider (Thomisus citrinellus) on a caper flower.

Flower Crab Spiders prey on a variety of insects – flies, hoverflies, bees, and sometimes other spiders.

Thomisus citrinellus with prey (hoverfly).
Thomisus citrinellus with prey (fly).
A white female, with a male riding piggyback, preying on a yellow female.

Flower Crab Spiders do not build webs, but they will spin silk thread to use as a drop line or to fold leaves into a tent-like structure where they can hide in ambush. Eggs are also laid in a silk dish covered with a lid.

Thomisus citrinellus with silk folding a leaf of a caper bush.
Thomisus citrinellus with its silk drop line visible.
A baby Flower Crab Spider (Thomisus citrinellus)

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