Misumena vatia is a species of crab spider with holarctic distribution. In North America, where it is the largest and best-known flower spider, it is called the goldenrod crab spider or flower (crab) spider, because it is commonly found hunting in goldenrod sprays in the autumn.
Young males in the early summer may be quite small and easily overlooked, but females can grow up to 10 mm (excluding legs); males reach 5 mm at most.
These spiders may be yellow or white, depending on the flower in which they are hunting. Especially younger females, which may hunt on a variety of flowers such as daisies and sunflowers, may change color "at will". Older females require large amounts of relatively large prey to produce the best possible clutch of eggs. They are therefore, in North America, most commonly found in goldenrod (Solidago sp.), a bright yellow flower which attracts large numbers of insects, especially in autumn. It is often very hard even for a searching human to recognize one of these spiders on a yellow flower.