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.
When a male finds a female, he climbs over her head over her opisthosoma onto her underside, where he inserts his pedipalps to inseminate her.
The young reach a size of about 5mm by autumn and spend the winter on the ground. They molt for the last time in May of the next year.
These spiders change color by secreting a liquid yellow pigment into the outer cell layer of the body. On a white base, this pigment is transported into lower layers, so that inner glands, filled with white guanine, become visible. If the spider dwells longer on a white plant, the yellow pigment is often excreted. It will then take the spider much longer to change to yellow, because it will have to produce the yellow pigment first. The color change is induced by visual feedback; spiders with painted eyes were found to have lost this ability. The color change from white to yellow takes between 10 and 25 days, the reverse about six days. The yellow pigments have been identified as kynurenine and 3-hydroxykynurenine.
Source:http://en.wikipedia.org/wiki/Misumena_vatia - 10.12.2011