Misumena vatia Clerck, 1757 ♀
Common names: Flowering crab spiders, Goldenrod Crab Spider [En], Misumène, Araignée-citron [Fr], Gewone kameleonspin [Nl], Veränderliche Krabbenspinne [De], Araña cangrejo [Es], Yengeç Örümceği [Tu]
BRUSSELS ● Belgium
Description: 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.
Biology: The much smaller males scamper from flower to flower in search of females and are often seen missing one or more of their legs. This may be due either to near misses by predators such as birds or to fighting with other males.
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.
Wikipedia, Misumena vatia
Acorn J., Sheldon I., 2003. Bugs of Ontario, Edmonton: Lone Pine Publishing.
Oxford G.S., Gillespie R.G., 1998. Evolution and Ecology of Spider Coloration, Annual Review of Entomology, Annual Reviews, vol. 43, p. 619-643