Crab spiders (family Thomisidae) are ambush predators that wait motionless on flowers, leaves, and bark for prey to come within reach. They are named for their crab-like posture — the first two pairs of legs are longer and held outstretched, and they can move sideways and backward. Arizona is home to numerous crab spider species, including the goldenrod crab spider (Misumena vatia), which can slowly change color between white and yellow to match the flower it is sitting on. Crab spiders do not spin capture webs. They are particularly common on flowering plants during Arizona's spring and monsoon seasons when pollinators are abundant. Despite their ability to catch bees and wasps much larger than themselves, they are completely harmless to humans.