Goldenrod Crab Spider
The Goldenrod Crab spider (Misumena vatia) is a species of crab spider which thrives in the northern hemisphere. This crab spider received the name Goldenrod Crab spider in North America, where it is the best-known and largest flower spider. This spider is frequently found hunting in brilliant yellow goldenrod sprays in the autumn. These spiders are generally hard to distinguish on a yellow flower, even for a searching human.
In the early summer the young males may be slightly small and overlooked reaching about 0.2 inches while the females can reach about 0.4 inches not including her legs. These spiders are usually white or yellow, depending on the flower which they are hunting. Particularly younger female Goldenrod Crab spiders, which hunt on a range of flowers such as sunflowers and daisies, can change color “at will”. The older females need large quantities of reasonably sizable prey to produce the best clutch of eggs.
Generally the males, which tend to be smaller, scurry from flower to flower looking for female Goldenrod Crab spiders. The male spider is usually seen missing one or more of his legs, generally due to near death experiences with birds and other predators, or because of fighting with other males. When the male spider finds the female spider he then climbs over her head and her opisthosma onto her underside, he then inserts his pedipalps to inseminate her.
Young Goldenrod Crab spiders reach about 0.2 inches in the autumn and spend the winter on the ground. In May, of the next year, they molt. These spiders secrete a yellow liquid pigment onto the outer cell layer of the body which is how they change color. When the spider is on a white base, this pigment is carried into bottom layers, so the inner glands may fill with white guanine, becoming visible. The yellow pigment is usually excreted if the spider roams longer on a white plant. Because it will have to produce the yellow pigment first it takes the spider much longer to change back to yellow. The color change is caused by visible response. It takes between 10 to 25 days for the color change from white to yellow, yet it takes about 6 days for the reverse. The yellow pigments have been identified as 3-hydroxykynurenine and kynurenine.