Crab Spider

Crab spider, Misumena vatia, on Rosebay Willowherb.  High Elms Country Park, 14 July 2011.

Crab spiders lurk in flowers, waiting for insects to come and feed on their pollen or nectar. Usually, they are the same colour as the flower, so it is odd that this one should be white; or rather, it is odd that it should have chosen this flower. It is capable of becoming more yellow than this one is, but that wouldn't help it here.

I saw several of the same species on the same flowers, back in the midsummer of 2011. There is also a glimpse of one in this post: Hemp-Agrimony with Crab Spider; at least those flowers have a whitish element.