Misumena vatia hunts by ambush on flower heads, gripping bees, flies and butterflies larger than itself with long forelegs and subduing them with venom. It spins no snare, and its concealment is the flower.
The colour change is pigment-based. To become yellow the female secretes an ommochrome pigment into the outer cell layer of the cuticle; to return to white she withdraws it into deeper tissue and excretes it. The forward direction takes something like ten to twenty-five days and the reverse about six, so a spider cannot follow a bloom that changes under it. Males do not change colour.
Whether the disguise works is less clear than it looks. Bees see ultraviolet, and crab spiders on some flowers reflect ultraviolet in a way that makes the flower more conspicuous, apparently drawing pollinators in. Experimental results on capture success in matched and mismatched pairings do not agree.