Goldenrod Crab Spider

Misumena vatia is a thomisid crab spider: females 6–11 mm with a squat, crab-like body and greatly elongated, laterally held front two leg pairs; males are 3–4 mm and dark-legged. Females can reversibly change between white and yellow over several days to match the flower they occupy, adding crimson lateral streaks in some individuals. Eggs are laid in a folded-leaf silk nest of 40–200, guarded until the female dies in autumn, with one generation per year and juveniles overwintering in leaf litter.

Crab spiders spin no capture web and instead sit motionless on a bloom with front legs held open, grabbing visiting bees, hoverflies and butterflies far larger than themselves and immobilising them with a fast-acting venom delivered through small fangs. They walk sideways and backwards like crabs and rely wholly on crypsis, freezing or dropping when approached. They are harmless to people — the fangs rarely penetrate skin and there is no medical significance — and are best regarded as an incidental garden species rather than a structural pest.