Crab Spiders (Family Thomisidae) are the most colorful spiders in Utah. They are "sit-and-wait" predators that prefer the bright petals of a garden to the dark corners of a basement.
Crab spiders get their name from their unique body shape and the way they move.
Crab-Like StanceTheir two front pairs of legs are much longer and stronger than their back legs, and they are usually held out to the sides in a "clasping" position.
Sideways ScuttleLike a true crab, these spiders are famous for their ability to walk sideways and backward just as easily as forward.
Color ShiftingSome Utah species, like the Flower Crab Spider, can actually change their color from white to yellow over several days to match the flower they are hiding on.
Crab spiders do not build webs. Instead, they rely on perfect camouflage and lightning-fast reflexes.
Flower DwellersYou will almost always find them perched on flowers or leaves. They sit perfectly still until a pollinator (like a fly or bee) lands, then they grab it with their powerful front legs.
The "Hitchhiker"When they are found inside Utah homes, it is almost always because they were brought in on fresh-cut flowers from the garden or on produce from a local farmers' market.
Active During the DayUnlike most spiders, crab spiders are diurnal, meaning they are active and hunting during the daylight hours.
Do they bite humans?Bites are extremely rare. Even if they do bite, their fangs are usually too small to pierce skin, and their venom is harmless to humans and pets.
Are they eating my garden plants?No. Crab spiders are strictly carnivorous. They actually protect your plants by eating the pests that would otherwise damage your flowers.
Should I be worried if I find one on my patio furniture?Not at all. They likely dropped from a nearby tree or shrub. They have no interest in moving into your home.
